
267 U.S. 317 (1925)
GEORGE W. BUSH & SONS COMPANY
v.
MALOY ET AL., CONSTITUTING THE PUBLIC SERVICE COMMISSION OF MARYLAND.
No. 185.
Supreme Court of United States.
Argued January 16, 1925.
Decided March 2, 1925.
ERROR TO THE COURT OF APPEALS OF THE STATE OF MARYLAND.
*318 Mr. William L. Rawls and Mr. George Weems Williams for plaintiff in error.
Mr. Thomas H. Robinson, Attorney General of the State of Maryland, and Mr. Edward H. Burke, Assistant Attorney General, for defendants in error.
*323 MR. JUSTICE BRANDEIS delivered the opinion of the Court.
A statute of Maryland prohibits common carriers of merchandise or freight by motor vehicle from using the public highways over specified routes without a permit. The Public Service Commission is charged with the duty to "investigate the expediency of granting said permit" when applied for; and it is authorized to refuse the same if it "deems the granting of such permit prejudicial to the welfare and convenience of the public." Laws of Maryland, 1922, c. 401, § 4.
George W. Bush & Sons Co. applied for a permit to do an exclusively interstate business as a common carrier of freight over specified routes, alleging its willingness and intention to comply with all applicable regulations concerning the operation of motor vehicles. After due hearing the permit was denied. This suit was brought in a court of the State to restrain the state officials from interfering *324 with such use of the company's trucks. The bill alleged, and it was admitted by demurrer, that the highways were not unduly congested; that they are so constructed that they can carry burdens heavier than that which would be imposed by plaintiff's trucks; that the operation of its trucks would impose no different burden upon the highways than the operation of the trucks of the same kind and character by private persons, which was freely permitted; and that, in refusing the permit, the Commission had considered merely "whether or not existing lines of transportation would be benefited or prejudiced and in this way the public interest affected." The plaintiff claimed that, regardless of permit, it was entitled to use the highways as a common carrier in exclusively interstate commerce. The trial court dismissed the bill. Its decree was affirmed by the highest court of the State. 143 Md. 570. The case is here on writ of error under § 237 of the Judicial Code.
This case presents two features which were not present in Buck v. Kuykendall, ante, p. 307, decided this day. The first is that the highways here in question were not constructed or improved with federal aid. This difference does not prevent the application of the rule declared in the Buck Case. The federal-aid legislation is of significance, not because of the aid given by the United States for the construction of particular highways, but because those acts make clear the purpose of Congress that state highways shall be open to interstate commerce. The second feature is that here the permit was refused by the Commission, not in obedience to a mandatory provision of the state statute, but in the exercise, in a proper manner, of the broad discretion vested in it. This difference also is not of legal significance in this connection. The state action in the Buck Case was held to be unconstitutional, not because the statute prescribed an arbitrary test for the granting of permits, or because the Director of *325 Public Works had exercised the power conferred arbitrarily or unreasonably, but because the statute as construed and applied invaded a field reserved by the Commerce Clause for federal regulation.
Reversed.
The separate opinion of MR. JUSTICE McREYNOLDS, delivered in this case and the one immediately preceding it, ante, p. 307.
I am of opinion that the courts below reached correct conclusions in these causes.
The States have spent enormous sums in constructing roads and must continue to maintain and protect them at great cost if they are to remain fit for travel.
The problems arising out of the sudden increase of motor vehicles present extraordinary difficulties. As yet nobody definitely knows what should be done. Manifestly, the exigency cannot be met through uniform rules laid down by Congress.
Interstate commerce has been greatly aided  amazingly facilitated, indeed  through legislation and expenditures by the States. The challenged statutes do not discriminate against such commerce, do not seriously impede it, and indicate an honest purpose to promote the best interests of all by preventing unnecessary destruction and keeping the ways fit for maximum service.
The Federal Government has not and cannot undertake precise regulations. Control by the States must continue, otherwise chaotic conditions will quickly develop. The problems are essentially local, and should be left with the local authorities unless and until something is done which really tends to obstruct the free flow of commercial intercourse.
The situation is similar to the one growing out of the necessity for harbor regulations. State statutes concerning pilotage, for example, have been upheld although they *326 amounted to regulation of interstate and foreign commerce. "They fall within that class of powers which may be exercised by the States until Congress has seen fit to act upon the subject." Olsen v. Smith, 195 U.S. 332, 341.
