opinion: Mr. Justice Murphy
  delivered the opinion of the Court.
  A California statute prohibits the sale or arrangement of any transportation over the public highways of the State if the transporting carrier has no permit from the Interstate Commerce Commission. The federal Motor Carrier Act has substantially the same provision. The question is whether the state act as applied in this case is invalid in view of the federal act.
  Respondents operate a travel bureau in Los Angeles, and receive commissions for arranging “share-expense” passenger transportation in automobiles. Owners of private cars desiring passengers for a trip register with respondents’ agency, as do prospective passengers. State lines are crossed in many of the trips. Until 1942 the federal act specifically exempted such “casual, occasional, or reciprocal” transportation. But in that year the Interstate Commerce Commission removed the exemption, as the Motor Carrier Act empowered it to do. Both the California and federal statutes now require respondents to sell transportation only in carriers having permits from the I. C. C.
  Respondents were prosecuted under the state act. They admitted their unlawful activity, but demurred to the criminal complaint on the sole ground that the state statute entered an exclusive congressional domain. The trial court disagreed, and entered a judgment of conviction, but the appellate court upheld respondents’ contention, and ordered the complaint dismissed. 87 Cal. App. 2d Supp. 921, 197 P. 2d 851. The case is here on certiorari, 335 U. S. 883.
  Certain first principles are no longer in doubt. Whether as inference from congressional silence, or as a negative implication from the grant of power itself, when Congress has not specifically acted we have accepted the Cooley case’s broad delineation of the areas of state and national power over interstate commerce. Cooley v. Port Wardens, 12 How. 299; Southern Pacific Co. v. Arizona, 325 U. S. 761, 768. See Ribble, State and National Power Over Commerce, ch. 10. Absent congressional action, the familiar test is that of uniformity versus locality: if a case falls within an area in commerce thought to demand a uniform national rule, state action is struck down. If the activity is one of predominantly local interest, state action is sustained. More accurately, the question is whether the state interest is outweighed by a national interest in the unhampered operation of interstate commerce.
  There is no longer any question that Congress can redefine the areas of local and national predominance, Prudential Insurance Co. v. Benjamin, 328 U. S. 408; Southern Pacific Co. v. Arizona, supra, at 769, despite theoretical inconsistency with the rationale of the Commerce Clause as a limitation in its own right. The words of the Clause — a grant of power — admit of no other result. When Congress enters the field by legislation, we try to discover to what extent it intended to exercise its power of redefinition; here we are closer to an intent that can be demonstrated with assurance, although we may employ presumptions grounded in experience in doubtful cases.
  But whether Congress has or has not expressed itself, the fundamental inquiry, broadly stated, is the same: does the state action conflict with national policy? The Cooley rule and its later application, Southern Pacific Co. v. Arizona, supra, the question of congressional “occupation of the field,” and the search for conflict in the very terms of state and federal statutes are but three separate particularizations of this initial principle.
  We restate the familiar because respondents would have us pronounce an additional rule: that when Congress has made specified activity unlawful, “coincidence is as ineffective as opposition,” and state laws “aiding” enforcement are invalid. Respondents seem to argue that this is as fundamental as the rule of conflict with national authority, and that it rests upon wholly independent premises.
  But respondents seize upon only one part of the familiar phrase in Charleston & W. C. R. Co. v. Varnville Furniture Co., 237 U. S. 597, 604. We said that when “Congress has taken the particular subject-matter in hand coincidence is as ineffective as opposition . . . .” See also, Pennsylvania R. Co. v. Public Service Comm’n, 250 U. S. 566, 569; Missouri P. R. Co. v. Porter, 273 U. S. 341, 346. Respondents’ argument assumes the stated premise — that Congress has “taken the particular subject-matter in hand,” to the exclusion of state laws. The Court could not have intended to enunciate a mechanical rule, to be applied whatever the other circumstances indicating congressional intent. Neither the language nor the facts of the cases cited support an approach in such marked contrast with this Court’s consistent decisional bases. The Varnville case struck down a South Carolina statute which had the effect of holding a connecting carrier liable for goods damaged in interstate commerce, when Congress had determined that the initial carrier should bear primary responsibility; the Pennsylvania Railroad case held invalid a state measure requiring a specified type of rear platform different from the detailed specifications of the Interstate Commerce Commission; and in the Porter case, the Court thought Congress intended to leave the terms of a uniform bill of lading to the I. C. C., and that state laws on the subject were meant to be ineffective. See Cloverleaf Butter Co. v. Patterson, 315 U. S. 148, 157-159.
  The “coincidence” rationale is only an application of the first principle of conflict with national policy. The phrase itself simply states that familiar rule. If state laws on commerce are identical with those of Congress, the Court may find congressional motive to exclude the states: Congress has provided certain limited penalties, “and a state law is not to be declared a help because it attempts to go farther than Congress has seen fit to go,” Varnville, supra, at 604 — that is, if Congress has “occupied the field.” But the fact of identity does not mean the automatic invalidity of state measures. Coincidence is only one factor in a complicated pattern of facts guiding us to congressional intent. As the Court stated in the Pennsylvania Railroad case, at 569, the “question whether Congress and its commissions acting under it have so far exercised the exclusive jurisdiction that belongs to it as to exclude the State, must be answered by a judgment upon the particular case.” Statements concerning the “exclusive jurisdiction” of Congress beg the only controversial question: whether Congress intended to make its jurisdiction exclusive.
  This has long been settled. Fox v. Ohio, 5 How. 410, announced uncertainly what United States v. Marigold, 9 How. 560, later made clear: that “the same act might, as to its character and tendencies, and the consequences it involved, constitute an offence against both the State and Federal governments, and might draw to its commission the penalties denounced by either, as appropriate to its character in reference to each.” 9 How. at 569. See Ex parte Siebold, 100 U. S. 371, 390; United States v. Lanza, 260 U. S. 377, 384. And see Union Brokerage Co. v. Jensen, 322 U. S. 202, 208.
  Asbell v. Kansas, 209 U. S. 251, is a further illustration. A Kansas statute provided criminal penalties for the importation of cattle from any point south of the State, except for immediate slaughter, without approval of the proper state officials or the Bureau of Animal Industry of the United States. The congressional Act, 32 Stat. 791, 792, allowed cattle to be transported into a state if inspected and passed by an inspector of the United States Bureau of Animal Industry. Violation of the federal act brought criminal sanctions. Yet we affirmed a conviction under the state law. We said that “if the state law conflicts with it [federal law] the state law must yield. But the law of Kansas now before us recognizes the supremacy of the national law and conforms to it.” 209 U. S. at 258. And see the similar problem and similar answer by Brandeis, J., for the Court in Dickson v. Uhlmann Grain Co., 288 U. S. 188.
  To limit our inquiry to respondents’ single standard would restrict us to unreality. For Congress is often explicit when it wishes state laws to conclude federal prosecution, to avoid the double punishment possible in a federal system. See, for example, 18 U. S. C. § 659, defining the crime of stealing from an interstate carrier; 18 U. S. C. § 660, misapplication of funds by an officer or employee of a carrier engaged in commerce. And when state enforcement mechanisms so helpful to federal officials are to be excluded, Congress may say so, as in the Labor Management Relations Act, 1947, 29 U. S. C. (Supp. I), § 160 (a). That Congress has specifically saved state laws in some instances, see, e. g., the Securities Act of 1933, 15 U. S. C. § 77r, indicates no general policy save clarity.
  Respondents’ automatic “coincidence means invalidity” theory, applied in an area as imbued with the state’s interest as is this one, see infra, would lead us to the conclusion that a state may not make a dealer in perishable agricultural commodities respect its laws on the fraudulent nonpayment of an obligation, if that fraud occurred after an interstate shipment, 7 U. S. C. § 499b (4), for Congress has not expressly saved such prosecutions. We would hold, too, that extortion or robbery from interstate commerce under 18 U. S. C. § 1951 or 18 U. S. C. § 2117 is immune from state action; that the wrecking of a bridge over an interstate railroad is an “exclusively federal” offense, 18 U. S. C. § 1992; that the transmittal of a ransom note in interstate commerce cannot be punished by local authorities, 18 U. S. C. § 875. And see 18 U. S. C. §§ 331, 472, 479. In short, we would be setting aside great numbers of state statutes to satisfy a congressional purpose which would be only the product of this Court’s imagination. We cannot agree that each of the problems under the statutes cited may not be resolved by examination of the whole case.
  . The question is whether Congress intended to override state laws identical with its own when it, through the Interstate Commerce Commission, regulated share-expense passenger automobile transportation, or whether it intended to let state laws stand. While the statute says nothing expressly on this point and we are aided by no legislative history directly in point, we know that normally congressional purpose to displace local laws must be clearly manifested. H. P. Welch Co. v. New Hampshire, 306 U. S. 79, and cases cited; Maurer v. Hamilton, 309 U. S. 598, 614; Kelly v. Washington, 302 U. S. 1, 11, 14; Mintz v. Baldwin, 289 U. S. 346. Or if the claim is conflict in terms, it “must be clear that the federal provisions are inconsistent with those of the state to justify the thwarting of state regulation.” Cloverleaf Butter Co. v. Patterson, supra, at 156. See also Hines v. Davidowitz, 312 U. S. 52, at 67.
  General propositions derived from the whole sweep of the Commerce Clause are often helpful, and we think those just stated are persuasive indications of congressional intent in the case now before us. But the quite separate Commerce Clause degree questions can be resolved only by careful scrutiny of the particular activity regulated. The Interstate Commerce Commission found these dangers present in the business of share-expense passenger transportation: abandonment of passengers before reaching the promised destination; personal injuries sustained by passengers because of irresponsible drivers, with attendant delay and expense; delays caused by arrest and detention of drivers for violations of traffic laws; crowded conditions in automobiles by reason of an excessive number of passengers and their baggage; and “annoyance, anxiety, or fright caused by reckless and improper driving by the automobile operators, by the bad mechanical condition of the vehicles used, by the fatigue of drivers operating the automobiles for long periods without adequate rest, or by the improper conduct of the drivers or other passengers.” Evidence of these evils led the I. C. C. to remove the exemption which had covered these respondents. Ex parte No. MC-35, 33 M. C. C. 69, 73, 74. See also Report of Federal Coordinator of Transportation on the Regulation of Transportation Agencies other than Railroads and on Proposed Changes in Railroad Regulation (Washington, 1934), Sen. Doc. 152, 73d Cong., 2d Sess., p. 226, mentioning the financial irresponsibility of these carriers. And see California v. Thompson, 313 U. S. 109.
  Of course we no longer limit the states to their “traditional” police powers in considering a statute’s validity under the Fourteenth Amendment. See Lincoln Federal Labor Union v. Northwestern Iron & Metal Co., 335 U. S. 525. But the tradition of “usual police powers” is still of aid in determining congressional intent to exclude state action on interstate commerce, at least when Congress has legislated. Many of the evils discussed by the I. C. C., above, are of the oldest within the ambit of the police power: protection against fraud and physical harm to a state’s residents. And consistent with the many cases giving the state’s interest in its own highways more weight than the national interest against “burdening” commerce, we have held that the highway regulation involved in this case is allowable state action before Congress acted. California v. Thompson, supra. Removal of the Motor Carrier Act’s exemption since the Thompson case does not change our conclusion.
  The case would be different if there were conflict in the provisions of the federal and California statutes. But there is no conflict in terms, and no possibility of such conflict, for the state statute makes federal law its own in this particular. The case might also be different were there variegated state laws on this subject in 1941, when the I. C. C. removed the federal exemption. We might then infer congressional purpose to displace local laws and establish a uniform rule beyond which states may not go. See Southern R. Co. v. Railroad Commission, 236 U. S. 439. Whatever the result in that class of cases, it would be startling to discover congressional intention to “displace” state laws when there were no state laws to displace when Congress acted. And that is nearly the situation in the present case. When the I. C. C. removed the federal exemption, it mentioned twelve cities, other than Los Angeles and San Francisco, in which the problem was particularly acute. Of these twelve cities, only two were located in states which attempted regulation of the kind of transportation we are now considering. Such striking absence of state law in states where the problem was recognized as serious by the I. C. C. clearly demonstrates a purpose to provide rather than displace local rules — to fill a void rather than nationalize a single rule. And we see nothing to show that a more serious problem in the State of California might not properly beget a more serious penalty, if the California legislature deemed it wise. I. C. C. recognition that the problem is more acute in some states than in others may well indicate acceptance of that proposition.
  It is said that I. C. C. recognition of the difficulties facing state regulation of interstate commerce, 33 M. C. C. at 76, because of cases such as Buck v. Kuykendall, supra, is of importance here. But this case concerns only the state's mechanisms for enforcing a statute identical with that of the federal government, though rooted in different policy considerations. We cannot predicate exclusion upon the simple recognition of Constitutional difficulties not present in the cause before us. Since the I. C. C. order was issued after California v. Thompson, one would expect the federal agency to be specific if it intended to supersede state laws. And we do not see how a previous California statute conflicting with I. C. C. policy, cf. 1933 Cal. Stat., c. 390, § 1, p. 1012, and Frank Broker Application, 8 M. C. C. 15, can have anything to do with the only California statute we are considering — a measure which does not conflict with I. C. C. policy. It is difficult to believe that the I. C. C. intended to deprive itself of effective aid from local officers experienced in the kind of enforcement necessary to combat this evil — aid of particular importance in view of the I. C. C.’s small staff. See 61st Annual Report of the I. C. C. (1947), p. 122; 62d Annual Report of the I. C. C. (1948), p. 109.
  This is not a hypothetical case on “normal Congressional intent.” It is California’s attempt to deal with a real danger to its residents. We know that coincidence, with its consequent possibility of double punishment, is an important factor to be considered. In many cases it may be a persuasive indication of congressional intent. But we must look at the whole case. In this case the factors indicating exclusion of state laws are of no consequence in the light of the small number of local regulations and the state’s normal power to enforce safety and good-faith requirements for the use of its own highways.
  “The state and federal regulations here applicable have their separate spheres of operation.” Union Brokerage Co. v. Jensen, supra, 322 U. S. at 208. So far as casual, occasional, or reciprocal transportation of passengers for hire is concerned, the State may punish as it has in the present case for the safety and welfare of its inhabitants; the nation may punish for the safety and welfare of interstate commerce. There is no conflict.
  Reversed.
  Calif. Stats. 1947, c. 1215, §§ 2, 4, pp. 2724, 2725, Deering’s Calif. Penal Code (1947 Supp.), §§654.1, 654.3. The statute makes it criminal to sell transportation in a carrier which has failed to secure a permit from either the California Public Utilities Commission or the Interstate Commerce Commission of the United States. Our only concern is with the correspondence of state and federal legislation.
  49 U. S. C. §§ 301, 303 (b) (see note 5, infra), 49 Stat. 543 et seq., 54 Stat. 919, 921. The act is limited to carriers operating in interstate commerce. 49 U. S. C. § 302 (b).
  49 U. S. C. §303 (b) (9).
  When the transportation is arranged “by a third-party intermediary who engages in making such transactions for compensation or as a regular occupation or business.” Ex parte No. MC-35, 33 M. C. C. 69, 81.
  The I. C. C. order was upheld by the District Court for the Northern District of Illinois in Drake v. United States, November 18, 1942 (see Levin v. United States, 3 Federal Carriers Cases (CCH) 2297). We affirmed. Levin v. United States, 319 U. S. 728.
  The Appellate Department of the Superior Court of Los Angeles County, State of California. There is no further review in the state courts. Art. VI, §§ 4, 4b, Calif. Const.; People v. Reed, 13 Cal. App. 2d 39, 56 P. 2d 240.
  Compare Missouri, K. & T. R. Co. v. Harris, 234 U. S. 412, with Northern P. R. Co. v. Washington, 222 U. S. 370; People v. Compagnie Generale Transatlantique, 107 U. S. 59, 63; Oregon-Washington R. & Nav. Co. v. Washington, 270 U. S. 87; and Cloverleaf Butter Co. v. Patterson, 315 U. S. 148. In these cases we made our decision concerning congressional intent by considering all the factors we considered relevant. We did not resort to a mechanical rule.
  The text also seems to supply the underlying rationale for the two cases cited in Varnville, at 604, to support the familiar quotation on “coincidence.” Southern R. Co. v. Railroad Comm’n, 236 U. S. 439, and Chicago, R. I. & P. R. Co. v. Hardwick Farmers Elevator Co., 226 U. S. 426. And see Jerome v. United States, 318 U. S. 101, 105.
  The Fox and Mangold cases were concerned with congressional power over forgeries, but for the purposes of this case the principle is the same.
  As might be expected: there was an exemption of casual operations when the statute was passed. See note 5, supra, and text. Discussion in debate and hearings is largely descriptive. See, e. g., Hearings before Subcommittee of House Committee on Interstate and Foreign Commerce on H. R. 5262 and H. R. 6016, 74th Cong., 1st Sess., pp. 47, 97, 183, 188-191, 208, 262; Hearings before Senate Committee on Interstate Commerce on S. 1629, S. 1632, and S. 1635, 74th Cong., 1st Sess., pp. 69, 70, 87, 97, 119, 186-188, 215, 390. The Committee reports are not helpful.
  There is, however, an expression of deference to state action on intrastate commerce, 49 U. S. C. §302 (b), as strengthened on the floor of the Senate, 79 Cong. Rec. 5735-5737. See 79 Cong. Rec. 12197; 49U.S. C.§305 (a).
  E. g., South Carolina State Highway Dept. v. Barnwell Bros., 303 U. S. 177; Clark v. Poor, 274 U. S. 554, 557; Maurer v. Hamilton, 309 U. S. 598, 614; Hendrick v. Maryland., 235 U. S. 610; H. P. Welch Co. v. New Hampshire, 306 U. S. 79; Kelly v. Washington, 302 U. S. 1, 10. See the distinction of Buck v. Kuykendall, 267 U. S. 307, and Bush & Sons v. Maloy, 267 U. S. 317, in Bradley v. Public Utilities Commission, 289 U. S. 92 at 95. See Kauper, State Regulation of Interstate Motor Carriers, 31 Mich. L. Rev. 920, 1097.
  “The travel-bureau business is quite extensive in many cities, particularly those in the western and southwestern States, notably at Kansas City, Mo., Wichita, Kans., Oklahoma City and Tulsa, Okla., Dallas, Forth Worth, San Antonio, Houston, and El Paso, Tex., Los Angeles and San Francisco, Calif., Portland, Oreg., Seattle, Wash., and Denver, Colo. The record establishes that such operations exist at other cities, including Chicago, Ill., and New York, N. Y. At one time, there were approximately 50 bureaus in operation in Los Angeles alone. . . .” 33 M. C. C. at 71-72.
  Letters from motor carrier commissions in western and southwestern States show that in 1941 there was no regulation, or attempt at regulation, covering Kansas City, Oklahoma City, Tulsa, Dallas, Fort Worth, San Antonio, Houston, El Paso, Portland, or Seattle. Only in Wichita and Denver was regulation attempted, and its extent in Wichita is not at all clear.
  In 1941 there was likewise no regulation or attempt at regulation of any kind in Arizona, Montana, New Mexico, or Utah, although Wyoming attempted some measure of control. Idaho’s only requirement was a registration fee.
  Respondents ignore practical differences when they rely upon the Southern R. Co. case, supra, which invalidated state regulation of grab-irons on railroad cars moving in interstate commerce. The individual state’s interest in the manner its residents use its own highways can hardly be compared with the time-honored I. C. C. control over the nation’s traditional avenues of interstate transportation, the railroads. A c.ase closer to the one before us is Asbell v. Kansas, supra. To recognize that the question is one of degree does not resolve the sharp differences in extreme revealed by the Southern R. Co. case and the one now before us.
  “The Federal Government has dealt with the manner in which the customhouse brokerage is carried on. Minnesota, however, is legitimately concerned with safeguarding the interests of its own people . . . .” Id.