delivered the opinion of the Court.
The facts of this case are simple and are not disputed. Appellant is a citizen of the United States and a resident of California. In December, 1939, he left his home in Marys-ville, California, for Spur, Texas, with the intention of bringing back to Marysville his wife’s brother, Frank Duncan, a citizen of the United States and a resident of Texas. *171When he arrived in Texas, appellant learned that Duncan had last been employed by the Works Progress Administration. Appellant thus became aware of the fact that Duncan was an indigent person and he continued to be aware of it throughout the period involved in this case. The two men agreed that appellant should transport Duncan from Texas to Marysville in appellant’s automobile. Accordingly, they left Spur on January 1, 1940, entered California by way of Arizona on January 3, and reached Marysville on January 5. When he left Texas, Duncan had about $20. It had all been spent by the time he reached Marysville. He lived with appellant for about ten days until he obtained financial assistance from the Farm Security Administration. During the ten day interval, he had no employment.
In Justice Court a complaint was filed against appellant under § 2615 of the Welfare and Institutions Code of California, which provides: “Every person, firm or corporation or officer or agent thereof that brings or assists in bringing into the State any indigent person who is not a resident of the State, knowing him to be an indigent person, is guilty of a misdemeanor.” On demurrer to the complaint, appellant urged that the Section violated several provisions of the Federal Constitution. The demurrer was overruled, the cause was tried, appellant was convicted and sentenced to six months imprisonment in the county jail, and sentence was suspended.
On appeal to the Superior Court of Yuba County, the facts as stated above were stipulated. The Superior Court, although regarding as “close” the question of the validity of the Section, felt “constrained to uphold the statute as a valid exercise of the police power of the State of California.” Consequently, the conviction was affirmed. No appeal to a higher state court was open to appellant. We noted probable jurisdiction early last *172term, and later ordered reargument (313 U. S. 545) which has been held.
At the threshold of our inquiry a question arises with respect to the interpretation of § 2615. On reargument, the Attorney General of California has submitted an exposition of the history of the Section, which reveals that statutes similar, though not identical, to it have been in effect in California since 1860. (See Cal. Stat. (1860) 213; Cal. Stat. (1901) 636; Cal. Stat. (1933) 2005). Neither under these forerunners nor under § 2615 itself does the term “indigent person” seem to have been accorded an authoritative interpretation by the California courts. The appellee claims for the Section a very limited scope. It urges that the term “indigent person” must be taken to include only persons who are presently destitute of property and without resources to obtain the necessities of life, and who have no relatives or friends able and willing to support them. It is conceded, however, that the term is not confined to those who are physically or mentally incapacitated. While the generality of the language of the Section contains no hint of these limitations, we are content to assign to the term this narrow meaning.
Article I, § 8 of the Constitution delegates to the Congress the authority to regulate interstate commerce. And it is settled beyond question that the transportation of persons is “commerce,” within the meaning of that provision.1 It is nevertheless true, that the States are not wholly precluded from exercising their police power in matters of local concern even though they may thereby affect inter*173state commerce. California v. Thompson, 313 U. S. 109, 113. The issue presented in this case, therefore, is whether the prohibition embodied in § 2615 against the “bringing” or transportation of indigent persons into California is within the police power of that State. We think that it is not, and hold that it is an unconstitutional barrier to interstate commerce.
The grave and perplexing social and economic dislocation which this statute reflects is a matter of common knowledge and concern. We are not unmindful of it. We appreciate that the spectacle of large segments of our population constantly on the move has given rise to urgent demands upon the ingenuity of government. Both the brief of the Attorney General of California and that of the Chairman of the Select Committee of the House of Representatives of the United States, as amicus curiae, have sharpened this appreciation. The State asserts that the huge influx of migrants into California in recent years has resulted in problems of health, morals, and especially finance, the proportions of which are staggering. It is not for us to say that this is not true. We have repeatedly and recently affirmed, and we now reaffirm, that we do not conceive it our function to pass upon “the wisdom, need, or appropriateness” of the legislative efforts of the States to solve such difficulties. See Olsen v. Nebraska, 313 U.S. 236, 246.
But this does not mean that there are no boundaries to the permissible area of State legislative activity. There are. And none is more certain than the prohibition against attempts on the part of any single State to isolate itself from difficulties common to all of them by restraining the transportation of persons and property across its borders. It is frequently the case that a State might gain a momentary respite from the pressure of events by the simple expedient of shutting its gates to the outside world. But, in the words of Mr. Justice Cardozo: “The Constitution was *174framed under the dominion of a political philosophy less parochial in range. It was framed upon the theory that the peoples of the several States must sink or swim together, and that in the long run prosperity and salvation are in union and not division.’’ Baldwin v. Seelig, 294 U.S. 511, 523.
It is difficult to conceive of a statute more squarely in conflict with this theory than the Section challenged here. Its express purpose and inevitable effect is to prohibit the transportation of indigent persons across the California border. The burden upon interstate commerce is intended and immediate; it is the plain and sole function of the statute. Moreover, the indigent non-residents who are the real victims of the statute are deprived of the opportunity to exert political pressure upon the California legislature in order to obtain a change in policy. South Carolina Highway Dept. v. Barnwell Bros., 303 U. S. 177, 185, n. 2. We think this statute must fail under any known test of the validity of State interference with interstate commerce.
It is urged, however, that the concept which underlies § 2615 enjoys a firm basis in English and American history.2 This is the notion that each community should care for its own indigent, that relief is solely the responsibility of local government. Of this it must first be said that we are not now called upon to determine anything other than the propriety of an attempt by a State to prohibit the transportation of indigent non-residents into its territory. The nature and extent of its obligation to afford relief to newcomers is not here involved. We do, however, suggest that the theory of the Elizabethan poor laws no longer fits the facts. Recent years, and particularly the past decade, have been marked by a growing recognition that in an industrial society the task of pro*175viding assistance to the needy has ceased to be local in character. The duty to share the burden, if not wholly to assume it, has been recognized not only by State governments, but by the Federal government as well. The changed attitude is reflected in the Social Security laws under which the Federal and State governments cooperate for the care of the aged, the blind and dependent children. U. S. C., Title 42, §§ 301-1307, esp. §§ 301, 501, 601, 701, 721,801,1201. It is reflected in the works programs under which work is furnished the unemployed, with the States supplying approximately 25% and the Federal government approximately 75% of the cost. See, e. g., Joint Resolution of June 26, 1940, c. 432, § 1 (d), 54 Stat. 611, 613. It is further reflected in the Farm Security laws, under which the entire cost of the relief provisions is borne by the Federal government. Id., at § § 2 (a), 2 (b), 2 (d).
Indeed, the record in this very case illustrates the inadequate basis in fact for the theory that relief is presently a local matter. Before leaving Texas, Duncan had received assistance from the Works Progress Administration. After arriving in California he was aided by the Farm Security Administration, which, as we have said, is wholly financed by the Federal government. This is not to say that our judgment would be different if Duncan had received relief from local agencies in Texas and California. Nor is it to suggest that the financial burden of assistance to indigent persons does not continue to fall heavily upon local and State governments. It is only to illustrate that in not inconsiderable measure the relief of the needy has become the common responsibility and concern of the whole nation.
What has been said with respect to financing relief is not without its bearing upon the regulation of the transportation of indigent persons. For the social phenomenon of large-scale interstate migration is as certainly a matter of national concern as the provision of assistance to those who have found a permanent or temporary abode. *176Moreover, and unlike the relief problem, this phenomenon does not admit of diverse treatment by the several States. The prohibition against transporting indigent non-residents into one State is an open invitation to retaliatory measures, and the burdens upon the transportation of such persons become cumulative. Moreover, it would be a virtual impossibility for migrants and those who transport them to acquaint themselves with the peculiar rules of admission of many States. “This Court has repeatedly declared that the grant [the commerce clause] established the immunity of interstate commerce from the control of the States respecting all those subjects embraced within the grant which are of such a nature as to demand that, if regulated at all, their regulation must be prescribed by a single authority.” Milk Control Board v. Eisenberg Farm Products, 306 U. S. 346, 351. We are of the opinion that the transportation of indigent persons from State to State clearly falls within this class of subjects. The scope of Congressional power to deal with this problem we are not now called upon to decide.
There remains to be noticed only the contention that the limitation upon State power to interfere with the interstate transportation of persons is subject to an exception in the case of “paupers.” It is true that support for this contention may be found in early decisions of this Court. In City of New York v. Miln, 11 Pet. 102, at 143, it was said that it is “as competent and as necessary for a State to provide precautionary measures against the moral pestilence of paupers, vagabonds, and possibly convicts, as it is to guard against the physical pestilence, which may arise from unsound and infectious articles imported, . . .” This language has been casually repeated in numerous later cases up to the turn of the century. See, e. g., Passenger Cases, 7 How. 283, 426 and 466-67; Railway Company v. Husen, 96 U. S. 465, 471; Plumley v. Massachusetts, 155 U. S. 461, 478; Missouri, K. & T. Ry. *177Co. v. Haber, 169 U. S. 613, 629. In none of these cases, however, was the power of a State to exclude “paupers” actually involved.
Whether an able-bodied but unemployed person like Duncan is a “pamper” within the historical meaning of the term is open to considerable doubt. See 53 Harvard L. Rev. 1031, 1032. But assuming that the term is applicable to him and to persons similarly situated, we do not consider ourselves bound by the language referred to. City of New York v. Miln was decided in 1837. Whatever may have been the notion then prevailing, we do not think that it will now be seriously contended that because a person is without employment and without funds he constitutes a “moral pestilence.” Poverty and immorality are not synonymous.
We are of the opinion that § 2615 is not a valid exercise of the police power of California; that it imposes an unconstitutional burden upon interstate commerce, and that the conviction under it cannot be sustained. In the view we have taken it is unnecessary to decide whether the Section is repugnant to other provisions of the Constitution.
Reversed.
Gloucester Ferry Co. v. Pennsylvania, 114 U. S. 196, 203; Leisy v. Hardin, 135 U. S. 100, 112; Covington Bridge Co. v. Kentucky, 154 U. S. 204, 218; Hoke v. United States, 227 U. S. 308, 320; Caminetti v. United States, 242 U. S. 470, 491; United States v. Hill, 248 U. S. 420, 423; Mitchell v. United States, 313 U. S. 80. Cf. The Federal Kidnaping Act of 1932, U. S. C., Title 18, §§ 408a-408c. It is immaterial whether or not the transportation is commercial in character. See Caminetti v. United States, supra.
See Hirsch, H. M., Our Settlement Laws (N. Y. Dept. of Social Welfare, 1933), passim.