opinion: Chief Justice Rehnquist
  delivered the opinion of the Court.
  In the Gun-Free School Zones Act of 1990, Congress made it a federal offense “for any individual knowingly to possess a firearm at a place that the individual knows, or has reasonable cause to believe, is a school zone.” 18 U. S. C. § 922(q)(1)(A) (1988 ed., Supp. V). The Act neither regulates a commercial activity nor contains a requirement that the possession be connected in any way to interstate commerce. We hold that the Act exceeds the authority of Congress “[t]o regulate Commerce . . . among the several States . . . .” U. S. Const., Art. I, §8, cl. 3.
  On March 10,1992, respondent, who was then a 12th~grade student, arrived at Edison High School in San Antonio, Texas, carrying a concealed .38-caliber handgun and five bullets. Acting upon an anonymous tip, school authorities confronted respondent, who admitted that he was carrying the weapon. He was arrested and charged under Texas law with firearm possession on school premises. See Tex. Penal Code Ann. § 46.03(a)(1) (Supp. 1994). The next day, the state charges were dismissed after federal agents charged respondent by complaint with violating the Gun-Free School Zones Act of 1990. 18 U. S. C. § 922(q)(1)(A) (1988 ed., Supp. V).
  A federal grand jury indicted respondent on one count of knowing possession of a firearm at a school zone, in violation of § 922(q). Respondent moved to dismiss his federal indictment on the ground that § 922(q) “is unconstitutional as it is beyond the power of Congress to legislate control over our public schools.” The District Court denied the motion, concluding that § 922(q) “is a constitutional exercise of Congress’ well-defined power to regulate activities in and affecting commerce, and the ‘business’ of elementary, middle and high schools . . . affects interstate commerce.” App. to Pet. for Cert. 55a. Respondent waived his right to a jury trial. The District Court conducted a bench trial, found him guilty of violating §922(q), and sentenced him to six months’ imprisonment and two years’ supervised release.
  On appeal, respondent challenged his conviction based on his claim that § 922(q) exceeded Congress’ power to legislate under the Commerce Clause. The Court of Appeals for the Fifth Circuit agreed and reversed respondent’s conviction. It held that, in light of what it characterized as insufficient congressional findings and legislative history, “section 922(q), in the full reach of its terms, is invalid as beyond the power of Congress under the Commerce Clause.” 2 F. 3d 1342, 1367-1368 (1993). Because of the importance of the issue, we granted certiorari, 511 U. S. 1029 (1994), and we now affirm.
  We start with first principles. The Constitution creates a Federal Government of enumerated powers. See Art. I, § 8. As James Madison wrote: “The powers delegated by the proposed Constitution to the federal government are few and defined. Those which are to remain in the State governments are numerous and indefinite.” The Federalist No. 45, pp. 292-293 (C. Rossiter ed. 1961). This constitutionally mandated division of authority “was adopted by the Framers to ensure protection of our fundamental liberties.” Gregory v. Ashcroft, 501 U. S. 452, 458 (1991) (internal quotation marks omitted). “Just as the separation and independence of the coordinate branches of the Federal Government serve to prevent the accumulation of excessive power in any one branch, a healthy balance of power between the States and the Federal Government will reduce the risk of tyranny and abuse from either front.” Ibid.
  The Constitution delegates to Congress the power “[t]o regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes.” Art. I, §8, cl. 3. The Court, through Chief Justice Marshall, first defined the nature of Congress’ commerce power in Gibbons v. Ogden, 9 Wheat. 1, 189-190 (1824):
  “Commerce, undoubtedly, is traffic, but it is something more: it is intercourse. It describes the commercial intercourse between nations, and parts of nations, in all its branches, and is regulated by prescribing rules for carrying on that intercourse.”
  The commerce power “is the power to regulate; that is, to prescribe the rule by which commerce is to be governed. This power, like all others vested in congress, is complete in itself, may be exercised to its utmost extent, and acknowledges no limitations, other than are prescribed in the constitution.” Id., at 196. The Gibbons Court, however, acknowledged that limitations on the commerce power are inherent in the very language of the Commerce Clause.
  “It is not intended to say that these words comprehend that commerce, which is completely internal, which is carried on between man and man in a State, or between different parts of the same State, and which does not extend to or affect other States. Such a power would be inconvenient, and is certainly unnecessary.
  “Comprehensive as the word ‘among’ is, it may very properly be restricted to that commerce which concerns more States than one.... The enumeration presupposes something not enumerated; and that something, if we regard the language, or the subject of the sentence, must be the exclusively internal commerce of a State.” Id., at 194-195.
  For nearly a century thereafter, the Court’s Commerce Clause decisions dealt but rarely with the extent of Congress’ power, and almost entirely with the Commerce Clause as a limit on state legislation that discriminated against interstate commerce. See, e. g., Veazie v. Moor, 14 How. 568, 573-575 (1853) (upholding a state-created steamboat monopoly because it involved regulation of wholly internal commerce); Kidd v. Pearson, 128 U. S. 1, 17, 20-22 (1888) (upholding a state prohibition on the manufacture of intoxicating liquor because the commerce power “does not comprehend the purely internal domestic commerce of a State which is carried on between man and man within a State or between different parts of the same State”); see also L. Tribe, American Constitutional Law 306 (2d ed. 1988). Under this line of precedent, the Court held that certain categories of activity such as “production,” “manufacturing,” and “mining” were within the province of state governments, and thus were beyond the power of Congress under the Commerce Clause. See Wickard v. Filburn, 317 U. S. 111, 121 (1942) (describing development of Commerce Clause jurisprudence).
  In 1887, Congress enacted the Interstate Commerce Act, 24 Stat. 379, and in 1890, Congress enacted the Sherman Antitrust Act, 26 Stat. 209, as amended, 15 U. S. C. § 1 et seq. These laws ushered in a new era of federal regulation under the commerce power. When cases involving these laws first reached this Court, we imported from our negative Commerce Clause cases the approach that Congress could not regulate activities such as “production,” “manufacturing,” and “mining.” See, e. g., United States v. E. C. Knight Co., 156 U. S. 1, 12 (1895) (“Commerce succeeds to manufacture, and is not part of it”); Carter v. Carter Coal Co., 298 U. S. 238, 304 (1936) (“Mining brings the subject matter of commerce into existence. Commerce disposes of it”). Simultaneously, however, the Court held that, where the interstate and intrastate aspects of commerce were so mingled together that full regulation of interstate commerce required incidental regulation of intrastate commerce, the Commerce Clause authorized such regulation. See, e. g., Shreveport Rate Cases, 234 U. S. 342 (1914).
  In A. L. A. Schechter Poultry Corp. v. United States, 295 U. S. 495, 550 (1935), the Court struck down regulations that fixed the hours and wages of individuals employed by an intrastate business because the activity being regulated related to interstate commerce only indirectly. In doing so, the Court characterized the distinction between direct and indirect effects of intrastate transactions upon interstate commerce as “a fundamental one, essential to the maintenance of our constitutional system.” Id., at 548. Activities that affected interstate commerce directly were within Congress’ power; activities that affected interstate commerce indirectly were beyond Congress’ reach. Id., at 546. The justification for this formal distinction was rooted in the fear that otherwise “there would be virtually no limit to the federal power and for all practical purposes we should have a completely centralized government.” Id., at 548.
  Two years later, in the watershed case of NLRB v. Jones & Laughlin Steel Corp., 301 U. S. 1 (1937), the Court upheld the National Labor Relations Act against a Commerce Clause challenge, and in the process, departed from the distinction between “direct” and “indirect” effects on interstate commerce. Id., at 36-38 (“The question [of the scope of Congress’ power] is necessarily one of degree”). The Court held that intrastate activities that “have such a close and substantial relation to interstate commerce that their control is essential or appropriate to protect that commerce from burdens and obstructions” are within Congress’ power to regulate. Id., at 37.
  In United States v. Darby, 312 U. S. 100 (1941), the Court upheld the Fair Labor Standards Act, stating:
  “The power of Congress over interstate commerce is not confined to the regulation of commerce among the states. It extends to those activities intrastate which so affect interstate commerce or the exercise of the power of Congress over it as to make regulation of them appropriate means to the attainment of a legitimate end, the exercise of the granted power of Congress to regulate interstate commerce.” Id., at 118.
  See also United States v. Wrightwood Dairy Co., 315 U. S. 110, 119 (1942) (the commerce power “extends to those intrastate activities which in a substantial way interfere with or obstruct the exercise of the granted power”).
  In Wickard v. Filburn, the Court upheld the application of amendments to the Agricultural Adjustment Act of 1938 to the production and consumption of homegrown wheat. 317 U. S., at 128-129. The Wickard Court explicitly rejected earlier distinctions between direct and indirect effects on interstate commerce, stating:
  “[Ejven if appellee’s activity be local and though it may not be regarded as commerce, it may still, whatever its nature, be reached by Congress if it exerts a substantial economic effect on interstate commerce, and this irrespective of whether such effect is what might at some earlier time have been defined as ‘direct’ or ‘indirect.’” Id., at 125.
  The Wickard Court emphasized that although Filburn’s own contribution to the demand for wheat may have been trivial by itself, that was not “enough to remove him from the scope of federal regulation where, as here, his contribution, taken together with that of many others similarly situated, is far from trivial.” Id., at 127-128.
  Jones & Laughlin Steel, Darby, and Wickard ushered in an era of Commerce Clause jurisprudence that greatly expanded the previously defined authority of Congress under that Clause. In part, this was a recognition of the great changes that had occurred in the way business was carried on in this country. Enterprises that had once been local or at most regional in nature had become national in scope. But the doctrinal change also reflected a view that earlier Commerce Clause cases artificially had constrained the authority of Congress to regulate interstate commerce.
  But even these modern-era precedents which have expanded congressional power under the Commerce Clause confirm that this power is subject to outer limits. In Jones & Laughlin Steel, the Court warned that the scope of the interstate commerce power “must be considered in the light of our dual system of government and may not be extended so as to embrace effects upon interstate commerce so indirect and remote that to embrace them, in view of our complex society, would effectually obliterate the distinction between what is national and what is local and create a completely centralized government.” 301 U. S., at 37; see also Darby, supra, at 119-120 (Congress may regulate intrastate activity that has a “substantial effect” on interstate commerce); Wickard, supra, at 125 (Congress may regulate activity that “exerts a substantial economic effect on interstate commerce”). Since that time, the Court has heeded that warning and undertaken to decide whether a rational basis existed for concluding that a regulated activity sufficiently affected interstate commerce. See, e. g., Hodel v. Virginia Surface Mining & Reclamation Assn., Inc., 452 U. S. 264, 276-280 (1981); Perez v. United States, 402 U. S. 146, 155-156 (1971); Katzenbach v. McClung, 379 U. S. 294, 299-301 (1964); Heart of Atlanta Motel, Inc. v. United States, 379 U. S. 241, 252-253 (1964).
  Similarly, in Maryland v. Wirtz, 392 U. S. 183 (1968), the Court reaffirmed that “the power to regulate commerce, though broad indeed, has limits” that “[t]he Court has ample power” to enforce. Id., at 196, overruled on other grounds, National League of Cities v. Usery, 426 U. S. 833 (1976), overruled by Garcia v. San Antonio Metropolitan Transit Authority, 469 U. S. 528 (1985). In response to the dissent’s warnings that the Court was powerless to enforce the limitations on Congress’ commerce powers because “[a]ll activities affecting commerce, even in the minutest degree, [Wickard], may be regulated and controlled by Congress,” 392 U. S., at 204 (Douglas, J., dissenting), the Wirtz Court replied that the dissent had misread precedent as “[njeither here nor in Wickard has the Court declared that Congress may use a relatively trivial impact on commerce as an excuse for broad general regulation of state or private activities,” id., at 197, n. 27. Rather, “[t]he Court has said only that where a general regulatory statute bears a substantial relation to commerce, the de minimis character of individual instances arising under that statute is of no consequence.” Ibid, (first emphasis added).
  Consistent with this structure, we have identified three broad categories of activity that Congress may regulate under its commerce power. Perez, supra, at 150; see also Hodel, supra, at 276-277. First, Congress may regulate the use of the channels of interstate commerce. See, e.g., Darby, 312 U. S., at 114; Heart of Atlanta Motel, supra, at 256 (“ ‘[T]he authority of Congress to keep the channels of interstate commerce free from immoral and injurious uses has been frequently sustained, and is no longer open to question’ ” (quoting Caminetti v. United States, 242 U. S. 470, 491 (1917))). Second, Congress is empowered to regulate and protect the instrumentalities of interstate commerce, or persons or things in interstate commerce, even though the threat may come only from intrastate activities. See, e. g., Shreveport Rate Cases, 234 U. S. 342 (1914); Southern R. Co. v. United States, 222 U. S. 20 (1911) (upholding amendments to Safety Appliance Act as applied to vehicles used in intrastate commerce); Perez, supra, at 150 (“[F]or example, the destruction of an aircraft (18 U. S. C. § 32), or... thefts from interstate shipments (18 U. S. C. § 659)”). Finally, Congress’ commerce authority includes the power to regulate those activities having a substantial relation to interstate commerce, Jones & Laughlin Steel, 301 U. S., at 37, i. e., those activities that substantially affect interstate commerce, Wirtz, supra, at 196, n. 27.
  Within this final category, admittedly, our case law has not been clear whether an activity must “affect” or “substantially affect” interstate commerce in order to be within Congress’ power to regulate it under the Commerce Clause. Compare Preseault v. ICC, 494 U. S. 1, 17 (1990), with Wirtz, supra, at 196, n. 27 (the Court has never declared that “Congress may use a relatively trivial impact on commerce as an excuse for broad general regulation of state or private activities”). We conclude, consistent with the great weight of our case law, that the proper test requires an analysis of whether the regulated activity “substantially affects” interstate commerce.
  We now turn to consider the power of Congress, in the light of this framework, to enact § 922(q). The first two categories of authority may be quickly disposed of: § 922(q) is not a regulation of the use of the channels of interstate commerce, nor is it an attempt to prohibit the interstate transportation of a commodity through the channels of commerce; nor can § 922(q) be justified as a regulation by which Congress has sought to protect an instrumentality of interstate commerce or a thing in interstate commerce. Thus, if § 922(q) is to be sustained, it must be under the third category as a regulation of an activity that substantially affects interstate commerce.
  First, we have upheld a wide variety of congressional Acts regulating intrastate economic activity where we have concluded that the activity substantially affected interstate commerce. Examples include the regulation of intrastate coal mining; Hodel, supra, intrastate extortionate credit transactions, Perez, supra, restaurants utilizing substantial interstate supplies, McClung, supra, inns and hotels catering to interstate guests, Heart of Atlanta Motel, supra, and production and consumption of homegrown wheat, Wickard v. Filburn, 317 U. S. 111 (1942). These examples are by no means exhaustive, but the pattern is clear. Where economic activity substantially affects interstate commerce, legislation regulating that activity will be sustained.
  Even Wickard, which is perhaps the most far reaching example of Commerce Clause authority over intrastate activity, involved economic activity in a way that the possession of a gun in a school zone does not. Roscoe Filburn operated a small farm in Ohio, on which, in the year involved, he raised 23 acres of wheat. It was his practice to sow winter wheat in the fall, and after harvesting it in July to sell a portion of the crop, to feed part of it to poultry and livestock on the farm, to use some in making flour for home consumption, and to keep the remainder for seeding future crops. The Secretary of Agriculture assessed a penalty against him under the Agricultural Adjustment Act of 1938 because he harvested about 12 acres more wheat than his allotment under the Act permitted. The Act was designed to regulate the volume of wheat moving in interstate and foreign commerce in order to avoid surpluses and shortages, and concomitant fluctuation in wheat prices, which had previously obtained. The Court said, in an opinion sustaining the application of the Act to Filburn’s activity:
  “One of the primary purposes of the Act in question was to increase the market price of wheat and to that end to limit the volume thereof that could affect the market. It can hardly be denied that a factor of such volume and variability as home-consumed wheat would have a substantial influence on price and market conditions. This may arise because being in marketable condition such wheat overhangs the market and, if induced by rising prices, tends to flow into the market and check price increases. But if we assume that it is never marketed, it supplies a need of the man who grew it which would otherwise be reflected by purchases in the open market. Home-grown wheat in this sense competes with wheat in commerce.” 317 U. S., at 128.
  Section 922(q) is a criminal statute that by its terms has nothing to do with “commerce” or any sort of economic enterprise, however broadly one might define those terms. Section 922(q) is not an essential part of a larger regulation of economic activity, in which the regulatory scheme could be undercut unless the intrastate activity were regulated. It cannot, therefore, be sustained under our cases upholding regulations of activities that arise out of or are connected with a commercial transaction, which viewed in the aggregate, substantially affects interstate commerce.
  Second, § 922(q) contains no jurisdictional element which would ensure, through case-by-case inquiry, that the firearm possession in question affects interstate commerce. For example, in United States v. Bass, 404 U. S. 336 (1971), the Court interpreted former 18 U. S. C. § 1202(a), which made it a crime for a felon to “receiv[e], posses[s], or transport] in commerce or affecting commerce . . . any firearm.” 404 U. S., at 337. The Court interpreted the possession component of § 1202(a) to require an additional nexus to interstate commerce both because the statute was ambiguous and because “unless Congress conveys its purpose clearly, it will not be deemed to have significantly changed the federal-state balance.” Id., at 349. The Bass Court set aside the conviction because, although the Government had demonstrated that Bass had possessed a firearm, it had failed “to show the requisite nexus with interstate commerce.” Id., at 347. The Court thus interpreted the statute to reserve the constitutional question whether Congress could regulate, without more, the “mere possession” of firearms. See id., at 339, n. 4; see also United States v. Five Gambling Devices, 346 U. S. 441, 448 (1953) (plurality opinion) (“The principle is old and deeply imbedded in our jurisprudence that this Court will construe a statute in a manner that requires decision of serious constitutional questions only if the statutory language leaves no reasonable alternative”). Unlike the statute in Bass, §922(q) has no express jurisdictional element which might limit its reach to a discrete set of firearm possessions that additionally have an explicit connection with or effect on interstate commerce.
  Although as part of our independent evaluation of constitutionality under the Commerce Clause we of course consider legislative findings, and indeed even congressional committee findings, regarding effect on interstate commerce, see, e. g., Preseault v. ICC, 494 U. S., at 17, the Government concedes that “[njeither the statute nor its legislative history contain[s] express congressional findings regarding the effects upon interstate commerce of gun possession in a school zone.” Brief for United States 5-6. We agree with the Government that Congress normally is not required to make formal findings as to the substantial burdens that an activity has on interstate commerce. See McClung, 379 U. S., at 304; see also Perez, 402 U. S., at 156 (“Congress need [not] make particularized findings in order to legislate”). But to the extent that congressional findings would enable us to evaluate the legislative judgment that the activity in question substantially affected interstate commerce, even though no such substantial effect was visible to the naked eye, they are lacking here.
  The Government argues that Congress has accumulated institutional expertise regarding the regulation of firearms through previous enactments. Cf. Fullilove v. Klutznick, 448 U. S. 448, 503 (1980) (Powell, J., concurring). We agree, however, with the Fifth Circuit that importation of previous findings to justify §922(q) is especially inappropriate here because the “prior federal enactments or Congressional findings [do not] speak to the subject matter of section 922(q) or its relationship to interstate commerce. Indeed, section 922(q) plows thoroughly new ground and represents a sharp break with the long-standing pattern of federal firearms legislation.” 2 F. 3d, at 1366.
  The Government’s essential contention, in fine, is that we may determine here that § 922(q) is valid because possession of a firearm in a local school zone does indeed substantially affect interstate commerce. Brief for United States 17. The Government argues that possession of a firearm in a school zone may result in violent crime and that violent crime can be expected to affect the functioning of the national economy in two ways. First, the costs of violent crime are substantial, and, through the mechanism of insurance, those costs are spread throughout the population. See United States v. Evans, 928 F. 2d 858, 862 (CA9 1991). Second, violent crime reduces the willingness of individuals to travel to areas within the country that are perceived to be unsafe. Cf. Heart of Atlanta Motel, 379 U. S., at 253. The Government also argues that the presence of guns in schools poses a substantial threat to the educational process by threatening the learning environment. A handicapped educational process, in turn, will result in a less productive citizenry. That, iii turn, would have an adverse effect on the Nation’s economic well-being. As a result, the Government argues that Congress could rationally have concluded that § 922(q) substantially affects interstate commerce.
  We pause to consider the implications of the Government’s arguments. The Government admits, under its “costs of crime” reasoning, that Congress could regulate not only all violent crime, but all activities that might lead to violent crime, regardless of how tenuously they relate to interstate commerce. See Tr. of Oral Arg. 8-9. Similarly, under the Government’s “national productivity” reasoning, Congress could regulate any activity that it found was related to the economic productivity of individual citizens: family law (including marriage, divorce, and child custody), for example. Under the theories that the Government presents in support of § 922(q), it is difficult to perceive any limitation on federal power, even in areas such as criminal law enforcement or education where States historically have been sovereign. Thus, if we were to accept the Government’s arguments, we are hard pressed to posit any activity by an individual that Congress is' without power to regulate.
  Although Justice Breyer argues that acceptance of the Government’s rationales would not authorize a general federal police power, he is unable to identify any activity that the States may regulate but Congress may not. Justice Breyer posits that there might be some limitations on Congress’ commerce power, such as family law or certain aspects of education. Post, at 624. These suggested limitations, when viewed in light of the dissent’s expansive analysis, are devoid of substance.
  Justice Breyer focuses, for the most part, on the threat that firearm possession in and near schools poses to the educational process and the potential economic consequences flowing from that threat. Post, at 619-624. Specifically, the dissent reasons that (1) gun-related violence is a serious problem; (2) that problem, in turn, has an adverse effect on classroom learning; and (3) that adverse effect on classroom learning, in turn, represents a substantial threat to trade and commerce. Post, at 623. This analysis would be equally applicable, if not more so, to subjects such as family law and direct regulation of education.
  For instance, if Congress can, pursuant to its Commerce Clause power, regulate activities that adversely affect the learning environment, then, a fortiori, it also can regulate the educational process directly. Congress could determine that a school’s curriculum has a “significant” effect on the extent of classroom learning. As a result, Congress could mandate a federal curriculum for local elementary and secondary schools because what is taught in local schools has a significant “effect on classroom learning,” cf. ibid., and that, in turn, has a substantial effect on interstate commerce.
  Justice Breyer rejects our reading of precedent and argues that “Congress . . . could rationally conclude that schools fall on the commercial side of the line.” Post, at 629. Again, Justice Breyer’s rationale lacks any real limits because, depending on the level of generality, any activity can be looked upon as commercial. Under the dissent’s rationale, Congress could just as easily look at child rearing as “fall[ing] on the commercial side of the line” because it provides a “valuable service — namely, to equip [children] with the skills they need to survive in life and, more specifically, in the workplace.” Ibid. We do not doubt that Congress has authority under the Commerce Clause to regulate numerous commercial activities that substantially affect interstate commerce and also affect the educational process. That authority, though broad, does not include the authority to regulate each and every aspect of local schools.
  Admittedly, a determination whether an intrastate activity is commercial or noncommercial may in some eases result in legal uncertainty. But, so long as Congress’ authority is limited to those powers enumerated in the Constitution, and so long as those enumerated powers are interpreted as having judicially enforceable outer limits, congressional legislation under the Commerce Clause always will engender “legal uncertainty.” Post, at 630. As Chief Justice Marshall stated in McCulloch v. Maryland, 4 Wheat. 316 (1819):
  “Th[e] [federal] government is acknowledged by all to be one of enumerated powers. The principle, that it can exercise only the powers granted to it... is now universally admitted. But the question respecting the extent of the powers actually granted, is perpetually arising, and will probably continue to arise, as long as our system shall exist.” Id., at 405.
  See also Gibbons v. Ogden, 9 Wheat., at 195 (“The enumeration presupposes something not enumerated”). The Constitution mandates this uncertainty by withholding from Congress a plenary police power that would authorize enactment of every type of legislation. See Art. I, § 8. Congress has operated within this framework of legal uncertainty ever since this Court determined that it was the Judiciary’s duty “to say what the law is.” Marbury v. Madison, 1 Cranch 137, 177 (1803) (Marshall, C. J.). Any possible benefit from eliminating this “legal uncertainty” would be at the expense of the Constitution’s system of enumerated powers.
  In Jones & Laughlin Steel, 301 U. S., at 37, we held that the question of congressional power under the Commerce Clause “is necessarily one of degree.” To the same effect is the concurring opinion of Justice Cardozo in Schechter Poultry:
  “There is a view of causation that would obliterate the distinction between what is national and what is local in the activities of commerce. Motion at the outer rim is communicated perceptibly, though minutely, to recording instruments at the center. A society such as ours ‘is an elastic medium which transmits all tremors throughout its territory; the only question is of their size.’” 295 U. S., at 554 (quoting United States v. A. L. A. Schechter Poultry Corp., 76 F. 2d 617, 624 (CA2 1935) (L. Hand, J., concurring)).
  These are not precise formulations, and in the nature of things they cannot be. But we think they point the way to a correct decision of this case. The possession of a gun in a local school zone is in no sense an economic activity that might, through repetition elsewhere, substantially affect any sort of interstate commerce. Respondent was a local student at a local school; there is no indication that he had recently moved in interstate commerce, and there is no requirement that his possession of the firearm have any concrete tie to interstate commerce.
  To uphold the Government’s contentions here, we would have to pile inference upon inference in a manner that would bid fair to convert congressional authority under the Commerce Clause to a general police power of the sort retained by the States. Admittedly, some of our prior cases have taken long steps down that road, giving great deference to congressional action. See supra, at 556-558. The broad language in these opinions has suggested the possibility of additional expansion, but we decline here to proceed any further. To do so would require us to conclude that the Constitution’s enumeration of powers does not presuppose something not enumerated, cf. Gibbons v. Ogden, supra, at 195, and that there never will be a distinction between what is truly national and what is truly local, cf. Jones & Laughlin Steel, supra, at 30. This we are unwilling to do.
  For the foregoing reasons the judgment of the Court of Appeals is
  Affirmed.
  The term “school zone” is defined as “in, or on the grounds of, a public, parochial or private school” or “within a distance of 1,000 feet from the grounds of a public, parochial or private school.” §921(a)(25).
  See also Hodel, 452 U. S., at 311 (“[SJimply because Congress may conclude that a particular activity substantially affects interstate commerce does not necessarily make it so”) (Rehnquist, J., concurring in judgment); Heart of Atlanta Motel, 379 U. S., at 273 (“[Wjhether particular operations affect interstate commerce sufficiently to come under the constitutional power of Congress to regulate them is ultimately a judicial rather than a legislative question, and can be settled finally only by this Court”) (Black, J., concurring).
  Under our federal system, the “ ‘States possess primary authority for defining and enforcing the criminal law.’” Brecht v. Abrahamson, 507 U. S. 619, 635 (1993) (quoting Engle v. Isaac, 456 U. S. 107, 128 (1982)); see also Screws v. United States, 325 U. S. 91, 109 (1945) (plurality opinion) (“Our national government is one of delegated powers alone. Under our federal system the administration of criminal justice rests with the States except as Congress, acting within the scope of those delegated powers, has created offenses against the United States”). When Congress criminalizes conduct already denounced as criminal by the States, it effects a “‘change in the sensitive relation between federal and state criminal jurisdiction.’” United States v. Enmons, 410 U. S. 396, 411-412 (1973) (quoting United States v. Bass, 404 U. S. 336, 349 (1971)). The Government acknowledges that § 922(q) “displaced] state policy choices in ... that its prohibitions apply even in States that have chosen not to outlaw the conduct in question.” Brief for United States 29, n. 18; see also Statement of President George Bush on Signing the Crime Control Act of 1990, 26 Weekly Comp, of Pres. Doc. 1944, 1945 (Nov. 29, 1990) (“Most egregiously, section [922(q)] inappropriately overrides legitimate State firearms laws with a new and unnecessary Federal law. The policies reflected in these provisions could legitimately be adopted by the States, but they should not be imposed upon the States by the Congress”).
  We note that on September 13,1994, President Clinton signed into law the Violent Crime Control and Law Enforcement Act of 1994, Pub. L. 103-322, 108 Stat. 1796. Section 320904 of that Act, id., at 2125, amends § 922(q) to include congressional findings regarding the effects of firearm possession in and around schools upon interstate and foreign commerce. The Government does not rely upon these subsequent findings as a substitute for the absence of findings in the first instance. Tr. of Oral Arg. 25 (“[W]e’re not relying on them in the strict sense of the word, but we think that at a very minimum they indicate that reasons can be identified for why Congress wanted to regulate this particular activity”).