opinion: Per Curiam.
  These cases are a sequel to our decision in City of Chicago v. United States, 396 U. S. 162, last; Term. The Chicago & Eastern Illinois Railroad (C&EI) filed a notice under § 13a (1) of the Interstate Commerce Act, 72 Stat. 571, 49 U. S. C. .§ 13a (1), proposing to discontinue a pair of trains known as the “Georgian,” operated by it between Chicago, Illinois, and Evansville, Indiana, and operated in conjunction with trains of the Louisville & Nashville Railroad (L&N) between.Evansville, Indiana, and Atlanta, Georgia, crossing Kentucky and Tennessee en route.. Part of-this litigation grows out of the ICC’s approval of the C&EI’s discontinuance of the Chicago-Evansville segment of the “Georgian,” evidenced by its termination of its investigation.
  The L&N also operates the “Hummingbird.” between Cincinnati, Ohio, and New Orleans, Louisiana. The “Hummingbird” connects with the “Georgian” at Nashville, Tennessee, where coaches and sleepers are transferred between the two trains. Following the ICC’s approval of C&EI’s discontinuance, the L&N served notice of discontinuance of the “Hummingbird” which the ICC also approved.
  In City of Chicago v. United States, supra, we held that ICC decisions to discontinue such an investigation were reviewable and remanded the cases- back to the District Court. That court then ordered consolidation . and remanded back to the ICC for further hearings, holding that the notice served by the C&EI on the Governors of Illinois and Indiana and at every station along the Chicago-Evansville run was inadequate because the people of Kentucky, Tennessee, and Georgia, and the Governors of those States were not notified. The “Hummingbird” discontinuance was also remanded to the ICC because of its close relationship with the “Georgian.” These appeals followed.
  We note jurisdiction and reverse. Section 13a (1) provides: .
  “A carrier or carriers subject to this part, if their rights with respect to the - discontinuance or change ... of the operation or service of any train . . . are súbject to any provision of the constitution or statutes of any State . ; . shall mail to the Governor of each State in which such train . .. . operated, and post in every station, depot or other facility served thereby, notice ... of any such proposed discontinuance or change.”
  This section, as we read it, required C&EI to give notice in Illinois and Indiana, the only- States in which the line now in controversy has operated. No provision is made in § 13a (1) for notice to States served by connecting railroads which might be affected by a discontinuance.
  The dissent finds ambiguity in the phrase “such train” in § 13a (1). It is argued that two interpretations of “such train” are possible: either the train of the C&EI between Chicago and Evansville or the “Georgian” between Chicago and Atlanta. By allowing discontinuance under § 13a (1), however, the ICC must have interpreted “such train” to refer to a train operated by one railroad only; and it. was only the Chicago-Evansville discontinuance that was before it at the time. The Commission ruled that: “Copies of the notices were duly served and posted in the manner required by section 13a (1) and our rules and regulations thereunder.” 331 I. C. C. 447, 448. We defer on this issue to the definition of “train” given by the administrative agency which has oversight of the problem. See, e. g., Udall v. Tallman, 380 U. S. 1, 16-17; Bowles v. Seminole Rock Co., 325 U. S. 410, 417-418.
  It is true that the C&EI and the L&-N functioned in close harmony. Discontinuance of service on one line might have a substantial effect on the other. But this relationship is not unique in railroading. Congress is not unaware of the mutual interdependence of railroads. It designed a federal regulatory system that displaced a state regulatory system when the state system could defeat a carrier’s attempt to discontinue a train. Hence we think it distorts § 13a (1) to treat if. so as to require the giving of notice to States which had no regulatory-power over the carrier.
  Accordingly, the decisions in No's. 386 and 410 are reversed. Since Nos. 387 and 396 were remanded to the Commission solely because of their relation to Nos. 386 and 410, those decisions are also reversed. The causes aré remanded to the District Court for review of any questions on the merits which may remain unresolved. •
  It is so ordered.
  No issue as to the adequacy of the notice given in the L&N proceeding is raised here.
  The regulation at the time provided for “[a] certificate [stating] that a copy of the notice * * * has been mailed to the Governor and railroad regulatory body of each State in which the subject train or ferry is operated.” (49 CFR § 143.5 (j),-formerly § 43.5 (j) (see 32 Fed. Reg. 5606)).
  Until 1958 railroad discontinuances required approval of the appropriate regulatory agency in each of the States in which the line operated. Congress knew of the financial difficulties of the railroads and concluded that the problem of discontinuance had to be removed from its parochial setting where state agencies 'too often required the “maintenance of uneconomic and unnecessary services and facilities.” S. Rep. No. 1647, 85th Cong.,'2d Sess., 22. Therefore, Congress vested power over discontinuances in a body aware of the national transportation problems and needs. See generally City of Chicago v. United States, 396 U. S. 162 (1969), and Southern R. Co. v. North Carolina, 376 U. S. 93 (1964).
  The problem of discontinuance of services as put to the Congress by the Association of American Railroads was described as follows: “[S]uch matters are subject to approval of State regulatory commissions and authority for. such discontinuances or abandonments must be obtained within the scope of statutes or procedures under which those State commissions operate.” Problems of the Railroads, Hearings before the Subcommittee on Surface Transportation of the Senate Committee on Interstate and Foreign Commerce, 85th Cong., 2d Sess., pt. 1, p. 25 (Jan. 13, 1958).
  The legislation was responsive to that need and may not be easily construed to do more than track the jurisdiction of a' State over the carrier in question.
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