opinion: PITTSBURGH & LAKE ERIE RAILROAD CO. v. RAILWAY LABOR EXECUTIVES’ ASSOCIATION
  CERTIORARI TO THE UNITED STATES COURT OF APPEALS FOR THE THIRD CIRCUIT
  No. 87-1589.
  Argued March 29, 1989
  Decided June 21, 1989
  Richard L. Wyatt, Jr., argued the cause for petitioner. With him on the briefs were Ronald M. Johnson, Charles L. Warren, Eric D. Within, and G. Edward Ytircon.
  Jeffrey P. Minear argued the cause for the United States as amicus curiae urging affirmance in both cases. With him on the brief were Solicitor General Fried and Deputy Solicitor General Merrill.
  John O’B. Clarke, Jr., argued the cause for respondents. With him on the brief for respondent Railway Labor Executives’ Association was William G. Mahoney. Robert S. Burk, Henri F. Rush, and John J. McCarthy, Jr., filed a brief for the Interstate Commerce Commission, respondent in No. 87-1888.
  Together with No. 87-1888, Pittsburgh & Lake Erie Railroad Co. v. Railway Labor Executives’ Association et al., also on certiorari to the same court.
  Briefs of amici curiae urging reversal in both cases were filed for the State of South Dakota by Richard A. Allen and Julie A. Tigges; and for the National Railway Labor Conference by Richard T. Conway, Ralph J. Moore, Jr., D. Eugenia Langan, and David P. Lee. Briefs of amici curiae urging reversal in No. 87-1888 were filed for the Airline Industrial Relations Conference by Harry A. Rissetto and Thomas E. Reinert, Jr.; for Chicago & North Western Transportation Co. et al. by Ral-ph J. Moore, Jr., D. Eugenia Langan, James P. Daley, Stuart F. Gassner, and Robert J. Corber; and for Guilford Transportation Industries, Inc., et al. by Ralph J. Moore, Jr., and D. Eugenia Langan.
  David Silberman and Laurence Gold filed a brief for the American Federation of Labor and Congress of Industrial Organizations as amicus curiae urging affirmance in No. 87-1589.
  Mark M. Levin filed a brief for the Regional Railroads of America et al. as amici curiae in both cases.
  Justice White
  delivered the opinion of the Court.
  These cases involve the interaction of three federal statutes with respect to the proposed sale of the rail line of the Pittsburgh and Lake Erie Railroad Co. (P&LE). The statutes are the Railway Labor Act (RLA), 44 Stat. 577, as amended, 45 U. S. C. § 151 et seq.; the Interstate Commerce Act (ICA), 49 U. S. C. §10101 et seq. (1982 ed. and Supp. V); and the Norris-LaGuardia Act (NLGA), 47 Stat. 70, 29 U. S. C. § 101 et seq.
  I
  Petitioner, P&LE, is a small rail carrier owning and operating 182 miles of rail line serving points in Ohio and western Pennsylvania and possessing trackage rights over other lines extending into New York. P&LE has experienced financial problems of increasing severity, having lost $60 million during the five years preceding the onset of these cases. After other efforts to improve its condition failed, notably work force reductions, concessions from its employees, and market expansion, P&LE decided that in order to recoup for its owners any part of their investments it must sell its assets. On July 8, 1987, P&LE agreed to sell its assets for approximately $70 million to a newly formed subsidiary, P&LE Rail Co., Inc. (Railco), of Chicago West Pullman Transportation Corporation (CWP). Railco intended to operate the railroad as P&LE had except that Railco would not assume P&LE’s collective-bargaining contracts with its various unions and would need only about 250 employees rather than the 750 then working for P&LE. When the unions representing P&LE’s employees were notified of the proposed sale, they asserted that the sale would have an effect on the working conditions of the carrier’s employees and therefore was subject to the requirements of the RLA, 45 U. S. C. §§ 152 Seventh and 156, which provide:
  “§ 152 . . . Seventh. Change in pay, rules, or working conditions contrary to agreement or to section 156 forbidden
  “No carrier, its officers, or agents shall change the rates of pay, rules, or working conditions of its employees, as a class, as embodied in agreements except in the manner prescribed in such agreements or in section 156 of this title.”
  “§ 156. Procedure in changing rates of pay, rules, and working conditions
  “Carriers and representatives of the employees shall give at least thirty days’ written notice of an intended change in agreements affecting rates of pay, rules, or working conditions, and the time and place for the beginning of conference between the representatives of the parties interested in such intended changes shall be agreed upon within ten days after the receipt of said notice, and said time shall be within the thirty days provided in the notice. In every case where such notice of intended change has been given, or conferences are being held with reference thereto, or the services of the Mediation Board have been requested by either party, or said Board has proffered its services, rates of pay, rules, or working conditions shall not be altered by the carrier until the controversy has been finally acted upon, as required by section 155 of this title, by the Mediation Board, unless a period of ten days has elapsed after termination of conferences without request for or proffer of the services of the Mediation Board.”
  The unions advised that they stood ready to negotiate all aspects of the matter, including the decision to sell the railroad assets. P&LE responded that it was willing to discuss the matter but that § 156 notice and bargaining were not required since the transaction was subject to the jurisdiction of the Interstate Commerce Commission (ICC or Commission) under the ICA and since the requirements of §§ 155 and 156 would intrude on that regime as well as upon management’s prerogatives to conduct the affairs of the company with respect to the sales transaction.
  Most of the unions then responded by themselves filing § 156 notices proposing changes in existing agreements to ameliorate the adverse impacts of the proposed sale upon P&LE’s employees. The unions sought guarantees that the sale would not cause any employee to be deprived of employment or to be placed in any worse position with respect to pay or working conditions and that P&LE would require that the purchaser of its rail line assume P&LE’s collective-bargaining agreements. P&LE again declined to bargain, asserting that the transaction was within the exclusive jurisdiction of the ICC. On August 19, respondent, Railway Labor Executives’ Association (RLEA), on behalf of P&LE’s unions, filed suit in the United States District Court for the Western District of Pennsylvania, seeking a declaratory judgment with respect to P&LE’s obligations under the RLA and an injunction against the sale pending completion of RLA bargaining obligations. On September 15, 1987, the unions went on strike. P&LE’s request for a restraining order against the strike was denied by the District Court on the ground that the NLGA forbade such an order.
  The proposed sale of assets could not be carried out without compliance with the terms of the ICA, 49 U. S. C. § 10901, which requires that noncarriers seeking to acquire a rail line first obtain a certificate of public convenience and necessity from the ICC. Section 10901(e) specifies the procedures for this purpose and provides that the ICC “may” require the acquiring company “to provide a fair and equitable arrangement for the protection of railroad employees who may be affected thereby no less protective of and beneficial to the interests of such employees than those established pursuant to section 11347 of this title.” Section 10505, however, authorizes the Commission to grant exemptions from the requirements of the Act when not necessary to carry out the national transportation policy. Based on its experience with acquisitions under § 10901, the ICC had issued what is known as the Ex Parte No. 392 Class Exemption, see Ex Parte No. 392 (Sub. No. 1), Class Exemption for the Acquisition and Operation of Rail Lines Under 4-9 U. S. C. 10901, 1 I. C. C. 2d 810 (1985) (Ex Parte 392), review denied sub nom. Illinois Commerce Comm’n v. ICC, 260 U. S. App. D. C. 38, 817 F. 2d 145 (1987)/' which provides abbreviated procedures for seeking approval for acquisitions by non-carriers such as Railco of an operating railroad or its assets. The regulatory procedure, see 49 CFR § 1150.32(b) (1987), involved the filing of an application for exemption which would become effective seven days after filing absent contrary notice from the Commission. An interested party could oppose the exemption by filing a petition to revoke at any time, after consideration of which the ICC could revoke the exemption in whole or in part or impose labor protective provisions. The ICC had indicated, however, that only in exceptional situations would such protective provisions be imposed.
  Accordingly, Railco on September 19, 1987, filed a notice of exemption pursuant to Ex Parte 392. After denying various requests by the unions to reject the notice of exemption and stay the sale, the Commission allowed the exemption to become effective on September 26. A petition to revoke filed by RLEA on October 2 is still pending before the Commission. At no time did RLEA request imposition of labor protective provisions pursuant to the Commission’s authority under § 10901.
  On October 5, 1987, P&LE reapplied to the District Court for an order restraining the strike. The District Court granted the request on October 8, ruling that the authorization of the sale by the ICC negated any duty that P&LE had to bargain over the effects of the sale on its employees, and that the NLGA did not forbid issuance of an injunction under such circumstances. On October 26, however, the Court of Appeals summarily reversed, holding that the ICA did not require accommodation of the NLGA’s restrictions on the District Court’s powers. 831 F. 2d 1231 (CA3 1987). A remand was ordered to determine whether the sale or strike violated the RLA. The unions did not resume their strike when the Court of Appeals reversed the District Court’s injunction, but threatened to do so if P&LE attempted to consummate the sale to Railco.
  The case in the District Court then went forward. Addressing the unions’ request for an injunction, the District Court held that although P&LE did not have a duty to bargain over its decision to sell, P&LE was required by the RLA to bargain over the effects of the sale on employees, and that the status quo provision of § 156 required that its bargaining obligations under the RLA must be satisfied before the sale could be consummated despite approval of the transaction by the ICC acting pursuant to the ICA. 677 F. Supp. 830 (WD Pa. 1987). A divided Court of Appeals affirmed the judgment of the District Court. 845 F. 2d 420 (CA3 1988).
  We granted P&LE’s petition in No. 87-1888, challenging the Court of Appeals’ affirmance of the injunction against the sale issued by the District Court, as well as P&LE’s petition in No. 87-1589, asking for reversal of the judgment of the Court of Appeals setting aside the strike injunction issued by the District Court. 488 U. S. 965 (1988).
  II
  In No. 87-1888, the issue is whether the RLA, properly construed, required or authorized an injunction against closing the sale of P&LE’s assets to Railco because of an unsatisfied duty to bargain about the effects of the sale on P&LE’s employees. We first address whether the RLA required P&LE to give notice of its decision to sell and to bargain about the effects of the sale. We then consider whether the unions’ own notices and the status quo provision of § 156 justified the injunction.
  A
  P&LE submits that neither its decision to sell nor the impact that sale of the company might have had on its employees was a “change in agreements affecting rates of pay, rules, or working conditions” (emphasis added) within the meaning of the RLA, 45 U. S. C. § 156, and that P&LE therefore had no duty to give notice or to bargain with respect to these matters. The Court of Appeals rejected this submission, focusing on the effects the sale would have on employees and concluding that the “loss of jobs by possibly two-thirds of the employees clearly would require a ‘change in agreements affecting rates of pay, rules, or working conditions.’” 845 F. 2d, at 428. The court did not point out how the proposed sale would require changing any specific provision of any of P&LE’s collective-bargaining agreements. It did not suggest that any of those agreements dealt with the possibility of the sale of the company, sought to confer any rights on P&LE’s employees in the event of the sale, or guaranteed that jobs would continue to be available indefinitely. What P&LE proposed to do would remove it from the railroad business and terminate its position as a railroad employer; and like the Court of Appeals, RLEA does not explain how such action would violate or require changing any of the provisions of the unions’ written contracts with P&LE.
  Of course, not all working conditions to which parties may have agreed are to be found in written contracts. Detroit & Toledo Shore Line R. Co. v. Transportation Union, 396 U. S. 142, 154-155 (1969) (Shore Line). It may be that “in the context of the relationship between the principals, taken as a whole, there is a basis for implying an understanding on the particular practice involved.” Id., at 160 (Harlan, J., dissenting). But the Court of Appeals did not purport to find an implied agreement that P&LE would not go out of business, would not sell its assets, or if it did, would protect its employees from the adverse consequences of such action. Neither does RLEA. We therefore see no basis for holding that P&LE should have given a § 156 notice of a proposed “change” in its express or implied agreements with the unions when it contracted to sell its assets to Railco. Nor was it, based on its own decision to sell, obligated to bargain about the impending sale or to delay its implementation. We find RLEA’s arguments to the contrary quite unconvincing.
  B
  There is more substance to the Court of Appeals’ holding, and to RLEA’s submission, that the unions’ § 156 notices proposed far-reaching changes in the existing agreements over which P&LE was required to bargain and that the status quo provision of § 156 prohibited P&LE from going forward with the sale pending completion of the “purposely long and drawn out” procedures which the Act requires to be followed in order to settle a “major” dispute. Railway Clerks v. Florida East Coast R. Co., 384 U. S. 238, 246 (1966). Section 156 provides that when a notice of change in agreements has been given, “rates of pay, rules, or working conditions shall not be altered by the carrier until the controversy has been finally acted upon, as required by section 155.” Relying on Shore Line, RLEA argues, and the Court of Appeals held, that when a rail labor union files a § 156 notice to change the terms of an agreement, the “working conditions” that the carrier may not change pending conclusion of the bargaining process are not limited to those contained in express or implied agreements but include, as Shore Line held, “those actual, objective working conditions and practices, broadly conceived, which were in effect prior to the time the pending dispute arose and which are involved in or related to that dispute.” 396 U. S., at 153. RLE A submits that the relationship of employer-employee and the state of being employed are among those working conditions that may not be changed until the RLA procedures are satisfied. We are unconvinced, for several reasons, that this is the case.
  The facts of Shore Line, briefly stated, were these: Shore Line operated 50 miles of rail line between Lang Yard in Toledo, Ohio, and Dearoad Yard near Detroit, Michigan. For many years, all train and engine crews reported for duty and finished the day at Lang Yard. When it was necessary to perform switching and other operations at other points, crews were transported at railroad expense to those outlying points. The company proposed to establish outlying work assignments at Trenton, Michigan, some 35 miles north of Lang Yard. Crews assigned there would have to report there. The proposed change was not forbidden by, and would not have violated, the parties’ collective-bargaining agreement. The union filed a § 156 notice seeking to amend the agreement to forbid the railroad to make outlying assignments. The issue was not settled by the parties and the union called for mediation. While the Mediation Board proceedings were pending, the railroad posted a bulletin creating the disputed assignment at Trenton. The union threatened a strike, the company sued to restrain the strike, and the union counterclaimed for an injunction relying on the status quo provision of § 156. The District Court and the Court of Appeals held for the union, and we affirmed over a dissent by Justice Harlan, joined by Chief Justice Burger. We held that even though Shore Line did not propose to change any of its agreements, the status quo provision of §156 — “rates of pay, rules, or working conditions shall not be altered” pending exhaustion of the required procedure — forbade any change by Shore Line in the “objective working conditions” then existing. 396 U. S., at 153. We noted that had it been the practice to make outlying work assignments, the company would have been within its rights to make the Trenton assignment; but the prior practice, the objective working condition, was to have crews report for work and come back to Lang Yard. That working condition could not be changed pending resolution of the dispute without violating the status quo provision of § 156 even though there was nothing in the agreement between the parties to prevent outlying assignments. Id., at 153-154.
  Shore Line, in our view, does not control these cases. In the first place, our conclusion in that case that the status quo provision required adherence not only to working conditions contained in express or implied agreements between the railroad and its union but also to conditions “objectively” in existence when the union’s notice was served, and that otherwise could be changed without violating any agreement, extended the relevant language of § 156 to its outer limits, and we should proceed with care before applying that decision to the facts of these cases. Second, reporting at Lang Yard, we thought, had been the unquestioned practice for many years, and we considered it reasonable for employees to deem it sufficiently established that it would not be changed without bargaining and compliance with the status quo provisions of the RLA. Third, and more fundamentally, the decision did not involve a proposal by the railroad to terminate its business. Here, it may be said that the working condition existing prior to the § 156 notice was that P&LE was operating a railroad through the agency of its employees, but there was no reason to expect, simply from the railroad’s long existence, that it would stay in business, especially in view of its losses, or that rail labor would have a substantial role in the decision to sell or in negotiating the terms of the sale. Whatever else Shore Line might reach, it did not involve the decision of a carrier to quit the railroad business, sell its assets, and cease to be a railroad employer at all, a decision that we think should have been accorded more legal significance than it received in the courts below. Our cases indicate as much.
  In Textile Workers v. Darlington Mfg. Co., 380 U. S. 263 (1965), an employer closed its textile mill when a union won a representation election. The National Labor Relations Board concluded that this action was an unfair labor practice under §§ 8(a)(1) and (3) of the National Labor Relations Act (NLRA). The Court of Appeals disagreed, holding that the complete or partial liquidation of an employer’s business even though motivated by antiunion animus was not an unfair practice. We affirmed in part, ruling that insofar as the NLRA is concerned, an employer “has an absolute right to terminate his entire business for any reason he pleases. . . .” 380 U. S., at 268. Whatever may be the limits of § 8(a)(1), we said, an employer’s decision to terminate its business is one of those decisions “so peculiarly matters of management prerogative that they would never constitute violations” of that section. Id., at 269. Neither would ceasing business and refusing to bargain about it violate § 8(a)(3) or § 8(a)(5) even if done with antiunion animus. Id., at 267, n. 5, 269-274. “A proposition that a single businessman cannot choose to go out of business if he wants to would represent such a startling innovation that it should not be entertained without the clearest manifestation of legislative intent or unequivocal judicial precedent so construing the Labor Relations Act.” Id., at 270. We found neither.
  Although Darlington arose under the NLRA, we are convinced that we should be guided by the admonition in that case that the decision to close down a business entirely is so much a management prerogative that only an unmistakable expression of congressional intent will suffice to require the employer to postpone a sale of its assets pending the fulfillment of any duty it may have to bargain over the subject matter of union notices such as were served in this litigation. Absent statutory direction to the contrary, the decision of a railroad employer to go out of business and consequently to reduce to zero the number of available jobs is not a change in the conditions of employment forbidden by the status quo provision of § 156. In these cases, P&LE concluded that it must sell its assets, and its agreement to sell to Railco, if implemented, would have removed it from the railroad business; no longer would it be a railroad employer. No longer would it need the services of members of the rail unions. The RLEA concedes that had the collective-bargaining agreements expressly waived bargaining concerning sale of P&LE’s assets, the unions’ § 156 notices to change the agreements could not trump the terms of the agreements and could not delay the sale. Brief for Respondent RLEA 44. We think the same result follows where the agreement is silent on the matter and the railroad employer has proceeded in accordance with the ICA. In these circumstances, there is little or no basis for the unions to expect that a § 156 notice would be effective to delay the company’s departure from the railroad business. Congress clearly requires that sales transactions like P&LE’s proposal must satisfy the requirements of the ICA, but we find nothing in the RLA to prevent the immediate consummation of P&LE’s contract to sell. When the ICC approved the sale by permitting the Ex Parte 392 exemption to become effective, P&LE was free to close the transaction and should not have been enjoined from doing so.
  This construction of the RLA also responds to our obligation to avoid conflicts between two statutory regimes, namely, the RLA and ICA, that in some respects overlap. As the Court has said, we “are not at liberty to pick and choose among congressional enactments, and when two statutes are capable of co-existence, it is the duty of the courts, absent a clearly expressed congressional intention to the contrary, to regard each as effective.” Morton v. Mancari, 417 U. S. 535, 551 (1974). We should read federal statutes “to give effect to each if we can do so while preserving their sense and purpose.” Watt v. Alaska, 451 U. S. 259, 267 (1981); see also United States v. Fausto, 484 U. S. 439, 453 (1988). We act accordingly in this litigation.
  Congress has exercised its Commerce Clause authority to regulate rail transportation for over a century. See Act to regulate commerce of 1887 (the ICA), ch. 104, 24 Stat. 379. In doing so, Congress has assigned to the ICC plenary authority over rail transactions, ranging from line extensions, consolidations, and abandonments, to acquisitions. In particular, the ICA in 49 U. S. C. § 10901(a) permits non-carriers to acquire a rail line only if the ICC determines that “the present or future public convenience and necessity require or permit” the rail acquisition and operation. The ICC may approve certification on satisfaction of various conditions. Specifically, it has authority to impose labor protection provisions though it is not obligated to do so. § 10901(e). Acting pursuant to § 10505, the ICC, in its Ex Parte 392 exemption proceedings, declared all noncarrier acquisitions presumptively exempt from § 10901 regulation. Such transactions would be deemed approved seven days after a notice filed by the acquiring entities. 49 CFR § 1150.32(b) (1987). And absent a showing of exceptional circumstances, which rail labor was entitled to demonstrate, labor protection provisions would not be imposed. The Ex Parte 392 procedures, and the ICA, § 10505 exemption authority generally, like amendments to ICA in the last two decades, see, e. g., the Railroad Revitalization and Regulatory Reform Act of 1976, Pub. L. 94-210, 90 Stat. 31; the Staggers Rail Act of 1980, Pub. L. 96-448, 94 Stat. 1895, aimed at reversing the rail industry’s decline through de-regulatory efforts, above all by streamlining procedures to effectuate economically efficient transactions.
  Here P&LE agreed to sell its assets to Railco. The transaction was presented to the ICC and an Ex Parte 392 exemption was requested. The ICC rejected the unions’ applications to stay or reject the exemption, which became effective seven days after it was requested. The unions then successfully sought an injunction delaying the closing of the transaction based on their § 156 notices. The Court of Appeals several times noted the tension between the two regimes, but concluded that the provisions of the RLA left no room for a construction easing those tensions. This was the case even though the injunction that was affirmed would likely result in cancellation of P&LE’s sale and the frustration of Congress’ intent through ICA amendments to deregulate the rail and air industries generally and more specifically to assist small rail lines with financial problems. We disagree with that conclusion, for as we have said, we are confident that the RLA is reasonably subject to a construction that would, at least to a degree, harmonize the two statutes. The injunction, which effectively prevented the sale from going forward, should not have been granted.
  c
  Our holding in these cases, which rests on our construction of the RLA and not on the pre-emptive force of the ICA, is that petitioner was not obligated to serve its own § 156 notice on the unions in connection with the proposed sale. We also conclude that the unions’ notices did not obligate P&LE to maintain the status quo and postpone the sale beyond the time the sale was approved by the Commission and was scheduled to be consummated. We do not hold, however, that P&LE had no duty at all to bargain in response to the unions’ § 156 motions. The courts below held, and RLEA agrees, that P&LE’s decision to sell, as such, was not a bargainable subject. The disputed issue is whether P&LE was required to bargain about the effects that the sale would or might have upon its employees. P&LE, in our view, was not entirely free to disregard the unions’ demand that it bargain about such effects. When the unions’ notices were served, however, the terms of P&LE’s agreement with Railco were more or less settled, and P&LE’s decision to sell on those terms had been made. To the extent that the unions’ demands could be satisfied only by the assent of the buyers, they sought to change or dictate the terms of the sale, and in effect challenged the decision to sell itself. At that time, P&LE was under no obligation to bargain about the terms it had already negotiated. To the extent that the unions’ proposals could be satisfied by P&LE itself, those matters were bargainable but only until the date for closing the sale arrived, which, of course, could not occur until the Ex Parte 392 exemption became effective. We are therefore constrained to reverse the Court of Appeals in No. 87-1888.
  III
  In No. 87-1589, the issue is whether the Court of Appeals was correct in setting aside the injunction against the strike issued on October 8, 1987. At that time, the Ex Parte 392 exemption had become effective, and the District Court held that because the ICC had in effect authorized the sale and had ruled that delay would be prejudicial to the parties and the public interests, the NLGA prohibition against issuing injunctions in labor dispute cases must be accommodated to the ICC’s decision that the sale of assets should go forward. It was this decision, based on the legal significance of the ICA and its impact on the NLGA, that the Court of Appeals summarily reversed. We agree with that decision.
  We have held that the NLGA § 4 general limitation on district courts’ power to issue injunctions in labor disputes must be accommodated to the more specific provisions of the RLA: “[T]he District Court has jurisdiction and power to issue necessary injunctive orders” to enforce compliance with the requirements of the RLA “notwithstanding the provisions of the Norris-LaGuardia Act.” Trainmen v. Howard, 343 U. S. 768, 774 (1952). Thus, a union may be enjoined from striking when the dispute concerns the interpretation or application of its contract and is therefore subject to compulsory arbitration. Trainmen v. Chicago River & Indiana R. Co., 353 U. S. 30 (1957). “[T]he specific provisions of the Railway Labor Act take precedence over the more general provisions of the Norris-LaGuardia Act.” Id., at 41-42. The same accommodation of the NLGA to the specific provisions of the NLRA must be made. A union that has agreed to arbitrate contractual disputes and is subject to a no-strike clause may be enjoined from striking despite the NLGA. Boys Markets, Inc. v. Retail Clerks, 398 U. S. 235 (1970).
  Petitioner contends that the NLGA must likewise be accommodated to the procedures mandated by Congress in 49 U. S. C. § 10901 specifically the authority of the ICC to impose labor protective provisions, the right of rail labor to seek such provisions from the ICC, and its right to judicial review if dissatisfied. It is urged that the ICA provides a comprehensive scheme for the resolution of labor protection issues arising out of ICC-regulated transactions and that rail labor must take advantage of those procedures rather than strike. We are unpersuaded that this is the case.
  The prohibition of the NLGA must give way when necessary to enforce a duty specifically imposed by another statute. But no applicable provision has been called to our attention that imposes any duty on rail unions to participate in ICC proceedings and to seek ICC protections with which they must be satisfied. Furthermore, labor protection provisions run against the acquiring railroad rather than the seller. Yet here it is with the seller, P&LE, that the unions wanted to bargain, seeking to ease the adverse consequences of the sale. To that end, the unions served § 156 notices, which at least to some extent obligated P&LE to bargain until its transaction was closed. We find nothing in the ICA that relieved P&LE of that duty, nor anything in that Act that empowers the ICC to intrude into the relationship between the selling carrier and its railroad unions. We are thus quite sure that the NLGA forbade an injunction against that strike unless the strike was contrary to the unions’ duties under the RLA.
  As to that issue, the Court of Appeals stated: “We intimate no view as to whether the provisions of the Railway Labor Act are applicable to this dispute so that the district court would be entitled to enjoin the strike while that Act’s dispute resolution mechanisms are underway. RLEA’s complaint seeking a declaration that the Railway Labor Act is applicable to this dispute is the merits issue before the district court.” 831 F. 2d, at 1237. On remand, the District Court held that the RLA was indeed applicable to the dispute and on that basis issued an injunction against P&LE. It did not, however, ever address the question whether the unions’ strike, which occurred after their suit was filed, was enjoin-able under the RLA. Neither did the Court of Appeals deal with that issue in affirming the District Court. P&LE perfunctorily asserts in its briefs in this Court that the strike injunction was proper because the unions were obligated to bargain rather than strike after their § 156 notices were served. RLEA did not respond to this assertion. With the case in this position, we shall not pursue the issue. Instead, we vacate the judgment of the Court of Appeals, and leave the matter, if it is a live issue, to be dealt with on remand.
  IV
  The judgment of the Court of Appeals in No. 87-1888 is reversed and the judgment in No. 87-1589 is vacated, and the cases are remanded for further proceedings consistent with this opinion.
  So ordered.
  Attempts to interest major rail lines in the property were unavailing because of the high cost of labor protection that would have been mandatory under the section of the ICA applicable to purchases by an existing carrier. 49 U. S. C. § 11347 (1982 ed., Supp. V), which is set forth in n. 7, infra.
  P&LE would keep certain real estate and some 6,000 railcars.
  CWP anticipated inviting all P&LE employees to submit applications and intended to give preference to them in hiring. CWP also expected to bargain for new contracts with the existing unions.
  Disputes about proposals to change rates of pay, rules, or working conditions are known as major disputes. Minor disputes are those involving the interpretation or application of existing contracts. The latter are subject to compulsory arbitration. The former are subject to the procedures set out in §§ 156 and 155, which specify the functions of the Mediation Board. In Trainmen v. Jacksonville Terminal Co., 394 U. S. 369, 378 (1969), we described the procedures applicable to major disputes:
  “The Act provides a detailed framework to facilitate the voluntary settlement of major disputes. A party desiring to effect a change of rates, pay, rules, or working conditions must give advance written notice. § 6. The parties must confer, § 2 Second, and if conference fails to resolve the dispute, either or both may invoke the services of the National Mediation Board, which may also proffer its services sua sponte if it finds a labor emergency to exist. § 5 First. If mediation fails, the Board must endeavor to induce the parties to submit the controversy to binding arbitration, which can take place, however, only if both consent. §§ 5 First, 7. If arbitration is rejected and the dispute threatens ‘substantially to interrupt interstate commerce to a degree such as to deprive any section of the country of essential transportation service, the Mediation Board shall notify the President,’ who may create an emergency board to investigate and report on the dispute. § 10. While the dispute is working its way through these stages, neither party may unilaterally alter the status quo. §§2 Seventh, 5 First, 6, 10.”
  The unions’ proposals were essentially these:
  “1. No employee of the P&LE Railroad Company who [was actively employed or on authorized leave of absencel between August 1, 1986 and August 1,1987 . . . shall be deprived of employment or placed in a worse position with respect to compensation or working conditions for any reason except resignation, retirement, death or dismissal for justifiable cause. . . . The formulae for the protective allowances, with a separation option, shall be comparable to those established in the Neiv York Dock conditions.
  “2. If an employee is placed in a worse position with respect to compensation or working conditions, that employee shall receive, in addition to a make-whole-remedy, penalty pay equal to three times the lost pay, fringe benefits and consequential damages suffered by such employee.
  “3. P&LE agrees to obtain binding commitments from any purchaser of its rail line operating properties and assets to assume all [of P&LE’s] collective bargaining agreements ... to hire P&LE employees in seniority order without physicals, and to negotiate with the P&LE and this Organization an agreement to apply this Agreement to the sale transaction and to select the forces to perform the work over the lines being acquired.” App. 38, 42, 46, 50, 54, 58, 62, 66, 122, 126.
  Section 4 of the NLGA, as set forth in 29 U. S. C. § 104, provides in part: “§ 104. Enumeration of specific acts not subject to restraining orders or injunctions
  “No court of the United States shall have jurisdiction to issue any restraining order or temporary or permanent injunction in any case involving or growing out of any labor dispute to prohibit any person or persons participating or interested in such dispute (as these terms are herein defined) from doing, whether singly or in concert, any of the following acts:
  “(a) Ceasing or refusing to perform any work or to remain in any relation of employment. . . .”
  Section 8 of that Act, as set forth in 29 U. S. C. § 108, is also relevant here:
  “§ 108. Noncompliance with obligations involved in labor disputes or failure to settle by negotiation or arbitration as preventing injunctive relief
  “No restraining order or injunctive relief shall be granted to any complainant who has failed to comply with any obligation imposed by law which is involved in the labor dispute in question, or who has failed to make every reasonable effort to settle such dispute either by negotiation or with the aid of any available governmental machinery of mediation or voluntary arbitration.”
  Title 49 U. S. C. § 11347 (1982 ed., Supp. V) requires labor protective provisions when a rail carrier is involved in certain transactions such as mergers or consolidations:
  “§ 11347. Employee protective arrangements in transactions involving rail carriers
  “When a rail carrier is involved in a transaction for which approval is sought under sections 11344 and 11345 or section 11346 of this title, the Interstate Commerce Commission shall require the carrier to provide a fair arrangement at least as protective of the interests of employees who are affected by the transaction as the terms imposed under this section before February 5, 1976, and the terms established under section 405 of the Rail Passenger Service Act (45 U. S. C. 565). Notwithstanding this subtitle, the arrangement may be made by the rail carrier and the authorized representative of its employees. The arrangement and the order approving the transaction must require that the employees of the affected rail carrier will not be in a worse position related to their employment as a result of the transaction during the 4 years following the effective date of the final action of the Commission (or if an employee was employed for a lesser period of time by the carrier before the action became effective, for that lesser period).”
  Section 10505 provides in part:
  “§ 10505. Authority to exempt rail carrier transportation
  “(a) In a matter related to a rail carrier providing transportation subject to the jurisdiction of the Interstate Commerce Commission under this subchapter, the Commission shall exempt a person, class of persons, or a transaction or service when the Commission finds that the application of a provision of this subtitle—
  “(1) is not necessary to carry out the transportation policy, of section 10101a of this title; and
  “(2) either (A) the transaction or service is of limited scope, or (B) the application of a provision of this subtitle is not needed to protect shippers from the abuse of market power.
  “(g) The Commission may not exercise its authority under this section ... (2) to relieve a carrier of its obligation to protect the interests of employees as required by this subtitle.”
  The Commission’s brief in this Court provides this background:
  “In the years just after the partial deregulation of the railroad industry occasioned by the passage of the Staggers Rail Act of 1980, Pub. L. No. 96-448, 94 Stat. 194-45, numerous new short lines and regional rail lines were created, pursuant to 49 U. S. C. 10901, through the sale of marginally profitable and unprofitable rail lines to new entities eager to provide rail service. In considering and approving these sales, the Commission became convinced that the expense imposed on such sales by the imposition of labor protective conditions was hampering the development of short line railroads and, indeed, was forcing the selling carriers to abandon these marginal lines pursuant to 49 U. S. C. 10903 of the ICA.
  “In order to foster the development of short line railroads to preserve rail facilities, service and employment that would otherwise be lost through abandonments, the Commission began withholding labor protections in individual sales. After considering over five years many such applications, the Commission determined that the formation of new rail carriers should be encouraged. In order to aid rail formations, the Commission promulgated the procedures in Ex Parte No. 392. In Ex Parte 392 the Commission exempted rail line sales to new carriers from full compliance with Commission procedures while retaining authority, under its revocation power, to review the transaction and correct any problem arising out of the transaction.” Brief for Interstate Commerce Commission 3-4 (footnote and citations omitted).
  In the Ex Parte 392 proceedings, the RLEA demanded that the Commission impose labor conditions in all § 10901 sale transactions. The Commission, however, ruled that labor protective provisions would be imposed in individual cases only upon a showing of exceptional circumstances. 1 I. C. C. 2d, at 815.
  The ICC modified the Ex Parte 392 procedure in 1988 to extend the waiting period from 7 to 35 days. See 53 Fed. Reg. 5981-5982 (1988).
  See n. 7, supra.
  The order was to remain in effect until the District Court ruled on the preliminary injunction sought by P&LE. It was this order that was reviewed by the Court of Appeals.
  The strike and the decisions of the Court of Appeals effectively terminated the proposed sale to Railco. Efforts to find another buyer were unsuccessful, but since P&LE is still interested in selling its assets and the issues in these cases have a bearing on those efforts, the cases, as the Court of Appeals recognized and the parties agree, ai'e not moot.
  Also, in late September, P&LE and its unions had informal exchanges about the effects of the sale. On October 14, one of the unions invoked the services of the Mediation Board. After the April 8, 1988, Court of Appeals decision, 845 F. 2d 420 (CA3), effects bargaining proceeded, and as these cases indicate, the parties have not resolved their differences.
  Indeed, the Court of Appeals stated that “P&LE’s agreements with its unions, however, do not appear to contemplate this type of transaction [i. e., sale of the rail lines], and thus neither expressly permit nor prohibit the sale.” 845 F. 2d, at 428, n. 9. RLEA asserts that P&LE had granted job security guarantees to some of its employees, see Brief for Respondent RLEA 3, but the record does not contain the collective-bargaining contracts, and if there were such guarantees, there is no claim that they would survive the sale of the rail line.
  Section 156 deals with bargaining and settlement procedures with respect to changes in agreements affecting rates of pay, rules, or working conditions. There must be notice of such intended changes, as well as bargaining and mediation if requested or proffered. And in every case involving such notice, i. e., of intended changes in agreements, rates of pay, rules or working conditions shall not be changed by the carrier until the specified procedures are satisfied. Because § 156 concerns changes in agreements, it is surely arguable that it is open to a construction that would not require the status quo with respect to working conditions that have never been the subject of an agreement, expressed or implied, and that, if no notice of changes had been served by the union, could be changed by the carrier without any bargaining whatsoever. Shore Line rejected that construction, but as indicated in the text, we are not inclined to apply Shore Line to the decision of P&LE to go out of business.
  We thought that a partial liquidation might present a different case and remanded for further findings. See 380 U. S., at 268, 276-277.
  In First National Maintenance Corp. v. NLRB, 452 U. S. 666 (1981), which, like Textile Workers v. Darlington Mfg. Co., arose under the NLRA, we concluded that “the harm likely to be done to an employer’s need to operate freely in deciding whether to shut down part of its business purely for economic reasons outweighs the incremental benefit that might be gained through the union’s participation in making the decision.” 452 U. S., at 686. Further, we held that the employer’s decision to close down a segment of its business “is not part of § 8 (d)’s ‘terms and conditions,’ . . . over which Congress has mandated bargaining.” Ibid. In so holding, we did not feel constrained by the Court’s decision in Railroad Telegraphers v. Chicago & N. W. R. Co., 362 U. S. 330 (1960). Indeed, we rejected the argument that Telegraphers compelled us to find bargaining over this decision mandatory. Although we pointed in First National Maintenance to the important distinctions between the RLA and the NLRA, there are other reasons why Telegraphers does not dictate the result in these cases. In Telegraphers, the Court held that the District Court was without jurisdiction to grant injunctive relief against a labor strike under the provisions of the NLGA. A closely divided Court reasoned that a railroad’s proposal to abandon certain single-agent stations and hence abolish some jobs was a bargainable issue. In Darlington and First National Maintenance, we concluded that the analysis in Telegraphers, which rested on an “expansive” reading of the RLA and the NLGA, did not govern a decision under the NLRA. 452 U. S., at 687, n. 23. In this case, we examine Telegraphers once again in the context of the RLA. In Telegraphers a railroad was seeking simply to eliminate or consolidate some of its little-used local stations. The railroad here, by contrast, sought to sell all its lines and go out of business. There is nothing in Telegraphers that forces us to reach the result, in this extreme case, that P&LE was prohibited from terminating its operations without first bargaining with the unions. Notwithstanding the policy considerations prompting the enlarged scope of mandatory bargaining under the RLA, in light of Darlington, which First National Maintenance reaffirmed, we are not inclined to extend Telegraphers to a case in which the railroad decides to retire from the railroad business.
  The dissent, post, at 518-520, seems to assert that Shore Line and Telegraphers dealt with a railroad’s freedom to leave the market. But as we point out, that is precisely what those cases did not involve. We are plainly at odds with the dissent with respect to the significance of P&LE’s decision to leave the railroad business.
  P&LE argues that the RLA injunction was an impermissible collateral attack on the ICC order approving the sale. But the ICA, 49 U. S. C. § 10901, and the RLA, 45 U. S. C. § 156, as we construe them, are complementary regimes. Here, the ICC simply granted an exemption from the strictures of § 10901, which permitted, but did not order, the consummation of the sale. It made no finding that would prevent enforcement of §156.
  The dissent, post, at 515, asserts that we ignore the principle that P&LE, a regulated utility, may not enter or leave the market without agency approval. Of course, we do not, for we set out the law that requires ICC consent to the sale, which was obtained.
  We address the duty to bargain about the effects of the sale only in the context of the facts existing when the unions’ notices were served. We do not deal with a railroad employer’s duty to bargain in response to a union’s § 156 notice proposing labor protection provisions in the event that a sale, not yet contemplated, should take place.