delivered the opinion of the Court.
We are called upon to determine whether a local police regulation unconstitutionally regulates or burdens interstate commerce.
Pennsylvania, by an Act of April 30, 1935 1 has declared the milk industry in that Commonwealth to be a business affected with a public interest. The statute defines a milk .dealer as any person “who purchases or handles milk within the Commonwealth for- sale, shipment, storage,' processing or manufacture within or without the Commonwealth.” It creates a Milk Control Board with authority to investigate, supervise, and regulate the industry and imposes penalties for violаtions of the law or of the Board's orders issued pursuant to the law, and requires a dealer to obtain a license by application to the Board. Licenses may be refused, suspеnded, or revoked for specified causes. A requisite of obtaining a license is that the dealer shall file with the Board a bond conditioned for the prompt payment of all amоunts due to producers for milk purchased by the licensee. The act empowers the Board to require the dealer to keep certain records and directs the Board, with the approval of the Governor, to “fix, by official order, the minimum prices to be paid by milk dealers to producers and others for milk.” The Board may vary the price according tо the production, use, form, grade or class of milk. 2
. The petitioner, the Milk Control Board, filed its bill in a Common Pleas Court to restrain the appellee from continuing to do business without complying with the statute. The respondent by its answer sought to justify *350 failure to comply on the ground that it was engaged in interstate commerce. After trial the court dismissed the bill. The Supreme Court of Pennsylvaniа affirmed the decree. 3
The respondent, a Pennsylvania corporation, leases and operates a milk receiving plant in Elizabethville, Pennsylvania, at which it buys milk from apprоximately one hundred and seventy-five farmers in the neighborhood, who bring their milk to the plant in their own cans. There the milk is weighed and tested by the respondent and emptied into large receiving tаnks in which. it is cooled preparatory to shipment. This requires retention of the milk for less than twenty-four hours; it is not processed, and no change occurs in its constituent elements. The milk is then drаwn from the cooling tanks into tank trucks operated by a contract carrier and transported into New York City for sale there by the respondent. The journey is continuous from Elizabethvillе to New York City. All milk purchased by the respondent at Elizabethville is shipped to and sold in New York. During the year 1934 approximately 4,500,000,000 pounds of milk were produced in Pennsylvania of which apрroximately 470,000,000 pounds were shipped out of the state.
The respondent contends that the act, if construed to require it to obtain a license, to file a bond for the proteсtion of producers, and to pay the farmers the prices prescribed by the Board, unconstitutionally regulates and burdens interstate commerce. The State Supreme Court has hеld that the statute is a valid police regulation. 4 The petitioner concedes that the purchase, shipment into *351 another state, and sale there of the milk in which the respondent deals is interstate commerce. The question for decision is whether, in the absence of federal regulation, the enforcement of the statute is prohibited by Article I, § 8 of the Constitution. We hold that it is not.
When the people declared “The Congress shall have Power ... To regulate Commerce . . . among the several States, . . .” their purpose was clear. The United States could n'ot exist as a nation if each of them were to hаve the power to forbid imports from another state, to sanction the rights of citizens to transport their goods interstate, or to discriminate as between neighboring states in admitting articlеs produced therein. The grant of the power of regulation to the Congress necessarily implies the subordination! of the states to that power. This court has repeatedly declared that the grant 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 naturе as to demand that, if regulated at all, their regulation must be prescribed by a single authority. 5 But in matters requiring diversity of treatment according to the special requirements of local conditions, the‘states remain free to act within their respective jurisdictions until Congress sees fit to act in the exercise of its overriding authority. 6 One of the commonest forms of state actiоn is the exercise of the police power directed to the control of local conditions and exerted in the interest of the welfare of the state’s citizens. Every state police statute necessarily will affect interstate commerce in some degree, but such a statute does not run counter to the grant of Congressional power merely because it incidentally or indirectly involves or burdens interstate commerce. This is so even though, *352 should Congress determine to exercise its paramount power, the state law might thereby bе restricted in operation or rendered unenforceable. 7 These principles have guided judicial decision for more than a century. Clearly they not only are inevitable' сorollaries of the constitutional provision, but their unimpaired enforcement is of the highest importance to the continued existence of our dual form of government. The difficulty аrises not in their statement or in a ready assent to their propriety, but in their application in connection with the myriad variations in the methods and incidents of commercial intercоurse.
The purpose of the statute under review obviously is to reach a domestic situation in the interest of the welfare of the producers and consumers of milk in Pennsylvania. Its provisiоns with respect to license, bond, and regulation of prices to be paid to producers are appropriate means ,to the ends: in view. The question is whether the prescription of prices to be paid producers in the effort to accomplish these ends constitutes a prohibited burden on interstate commerce, or an incidental burden whiсh'is permissible until superseded by Congressional enactment. That question can be answered only by weighing the nature of the respondent’s activities, and the propriety of local regulаtion of them, as disclosed by the record.
The respondent maintains a receiving station in Pennsylvania where it conducts the local business of buying milk.. At that station the neighboring farmers deliver their milk. The activity affected by the regulation is essentially local in Pennsylvania. Upon the completion of that transaction the respondent engages in conserving and transporting its own property. The Commonwealth does not essay to regulate or to restrain the shipment of the respondent’s milk into. New York or to regulate its sale or the price at which respondent may sell it in New York. *353 If dealers conducting receiving stations, in various localities in Pennsylvania were free to ignore the requirements of the statute on the ground that all or a part оf the milk they purchase is destined to another state the uniform operation of the statute locally would be crippled and might be impracticable. Only a small fraction of the milk produced by farmers in Pennsylvania is shipped out of the Commonwealth. There is, therefore, a comparatively large field remotely affecting and wholly unrelated to interstate commerce within which the statute operates. These considerations we think justify the conclusion that the effect of the law on interstate commerce is incidental and not forbiddеn by the Constitution, in the absence of regulation by Congress.
None of the decisions on which the court below and the respondent rely rules the instant case.
DiSanto
v.
Pennsylvania,
The decree must be reversed and the cause remanded for further proceedings not inconsistent with this оpinion.
Reversed.
[Over.]
Notes
P. L. 96; 31 P. S. § 684.
The act was repealed by an Act of April 28, 1937, P. L. 417, but all proceedings under it were saved by § 1203 of the later act. See
Commonwealth
v.
Ortwein,
See the opinion below, and
Colteryahn Sanitary Dairy
v.
Milk Control Comm’n,
Minnesota Rate Cases,
Ibid.
Ibid., pp. 402-403.