Me. Justice GS-bay,

after stating the case, delivered the opinion of the court.

The line of railroad communication, crossing the OhioBiver at Cairo, and of which the Illinois Central Bailroad forms part, has been established by Congress as a national highway for the accommodation, of interstate commerce and of the mails of the United States, and as such has been recognized and promoted by the State of Illinois. This will clearly *150 appear by a brief recapitulation of the acts of Congress and the statutes of Illinois upon the subject.

Congress, in the act of September 20, 1850, c. 61, granted a right of way, and sections of the public lands, to the State of Illinois, to aid in the construction of a railroad in that State from the southern termination of the Illinois and Michigan Canal “ to a point at or near the junction of the Ohio and Mississippi Rivers,” with branches to Chicago and Dubuque, “to be and remain a public highway, for the use of the government of the United States, free from toll or other charge upon the transportation of any property or troops of the United States,” and on which the United States mail should “ at all times be transported, under the direction of the Post Office Department, at such price as the. Congress may by law direct;” and, in order “ to aid in the construction of said Central Railroad,” made like grants to the States of Alabama and Mississippi, respectively, for the purpose of aiding in the construction of a railroad from the city of Mobile “ to a point near the mouth of the Ohio River.” 9 Stat. 466.

The manifest purpose of Congress was to establish a railroad in the centre of the Continent, connecting the waters of the Great Lakes with those of the Gulf of Mexico, for the benefit of interstate commerce, as well as of the military and postal departments of the government of the United States.

. The State of Illinois, by a statute of February 10, 1851, chartered the Illinois Central Railroad Company, and ceded to it the rights and lands granted to the State by the act of Congress, for the purpose of constructing and maintaining within the State such a trunk line and branches, describing its southern terminus as “ a point at the city of Cairo,” and declaring “ said road and branches to be free for the use of the United States, and to be employed by the Post-Office Department, as provided in said act of Congress; ” and (as if that were not sufficient) by another statute, a week later, the State expressly accepted the act of Congress, and agreed to be bound by the conditions expressed therein.

By the statute of Illinois of February 2, 1855, all railroad corporations of the State were empowered to make contracts *151 with, each other, and with railroad corporations of other States, for leasing, or running, or connecting their railroads; and by the statute of Illinois of February 25, 1867, railroads terminating at a point at which there was a railroad bridge on a line of continuous railroad thoroughfare were required to be connected by rail, as to make “ an uninterrupted communication over such railroads and bridge as public thoroughfares.”

By the act of June 15, 1866, c. 124, Congress, for the declared purpose of facilitating commerce among the several States, and the postal and military communications of the United States, authorized every railroad company in the United States, whose road was operated by steam, to carry over its road, bridges and ferries, as well passengers and freight, as government mails, troops and supplies, from one State to auother; and to connect, in any State authorizing it to do so, with roads of other States, so as to form continuous lines of transportation. 14 Stat. 66.

By the acts of Congress of December 17, 1872, c. 4, and February 14,1883, c. 44, bridges were authorized to be built across the Ohio Biver by any person or corporation, having lawful authority therefor, and with the approval of the Secretary of "War; and were declared to be lawful structures and post routes for the transmission of the mails and the troops and munitions of war of the United States. 17 Stat. 398; 22 Stat. 414.

It is not denied that the bridge across the Ohio Biver from the Kentucky shore to the Illinois shore, opposite the city of Cairo, was constructed by lawful authority, and as permitted by Congress. Nor is it denied that the Illinois Central Bail-road Company had the right, under the acts of Congress and the statutes of Illinois, to connect its road with that bridge, and to run its southward bound trains over that bridge as part of a system of interstate communication.

But it is contended, on behalf of the State of Illinois, that the station of the Illinois Central Bailroad Company, at the southern terminus of its road in the city of Cairo, having been originally established, and still remaining, at a point some three and a half miles from so much of its main line as forms *152 part of the through communication by railroad from the State of Illinois across the Ohio River to the State of Kentucky and other Southern States, the corporation is obliged, by a statute of the State of Illinois, to cause all its trains, including the fast mail train from Chicago to New Orleans, to be brought down to that station, and to stop there long enough to receive and let off passengers with safety.

The statute in question is as follows: “ Every railroad corporation shall cause its passenger trains to stop upon its arrival at each station, advertised by such corporation as a place for receiving and discharging passengers upon and from such trains, a sufficient length of time to receive and let off such passengers with safety: Provided, all regular passenger trains shall stop a sufficient length of time, at the railroad station of county seats, to receive and let off passengers with safety.” Illinois Rev. Stat. of 1889, c. 114, § 88.

It was argued, in behalf of the railroad company, that the whole effect of this section, was to require each train “ to stop upon its arrival” at a station, long enough to receive and let off passengers with safety; that the first part of the section only required trains to stop upon arrival “ at each station advertised as a place for receiving and discharging passengers upon and from such trains;” that the proviso merely required trains to stop, for a like time, on arriving at “the railroad station of county seats,” although not so advertised; and that no part of the section required any train to arrive at, or to go to, any particular station.

The Supreme Court of the State, however, held that the statute not only required every train to stop at every county seat at which it arrived, but that, as Cairo was admitted to be a county seat, the statute required every train passing through the city of Cairo to go to and stop at the station in that city. The construction given to the statute in this particular by the state court does not involve any Federal question, and must be accepted by this court in judging of the constitutionality of the statute. Chicago &c. Railway v. Minnesota, 134 U. S. 418, 456.

But the decision that the statute, so construed, was not an unconstitutional interference with interstate commerce, or *153 with the carrying of the mails by the United States, was a decision in favor of the validity of a state statute whose validity was drawn in question on the ground of its being repugnant to the Constitution and laws of the United States, as well as a decision against a right specially set up and claimed under the national Constitution and laws; and is therefore clearly reviewable by this court.

The effect of the statute of Illinois, as construed and applied by the Supreme Court of the State, is to require a fast mail train, carrying interstate passengers and the United States mail, from Chicago in the State of Illinois to places south of the Ohio River, over an interstate highway established by authority of Congress, to délay the transportation of such passengers and mails, by turning aside from the direct interstate route, and running to a station three miles and a half away from a point on that route, and back again to the same point, and thus travelling seven miles which form no part of its course, before proceeding on its way; and to do this for the purpose of discharging and receiving passengers at that station, for the interstate travel to and from which, as is admitted in this case, the railroad company furnishes other and ample accommodation.

This court is unanimously of opinion that this requirement is an unconstitutional hindrance and obstruction of interstate commerce, and of the passage of the mails of the United States.

Upon the state of facts presented by this record, the duties of the Illinois Central Railroad Company were not confined to those which it owed to the State of Illinois under the charter of the company and other laws of the State; but included distinct duties imposed upon the corporation by the Constitution and laws of the United States.

The State may doubtless compel the railroad company to perform the duty imposed by its charter of carrying passengers and goods between its termbi within the State. But so long, at least, as that duty is adequately performed by the company, the State cannot, under the guise of compelling its performance, interfere with the performance of paramount *154 duties to which the company has been subjected by the Constitution and laws of the United States.

The State may make reasonable regulations to secure the safety of passengers, even on interstate trains, while within its borders. But the State can do nothing which will directly burden or impede the interstate traffic of the company, or impair the usefulness of its facilities for such traffic. Railroad Co. v. Richmond, 19 Wall. 581, 589; Stone v. Fanners’ Loan & Trust Co., 116 U. S. 307, 331; Smith v. Alabama, 121 U. S. 165.

It may well be, as held by the courts of Illinois, that the arrangements made by the company with the Post-Office Department of the United States cannot have the effect of abrogating a reasonable police regulation of the State. But a statute of the State, which unnecessarily interferes with the speedy and uninterrupted carriage of the mails of the United States, cannot be considered as a reasonable police regulation.

In Union Pacific Railroad v. Hall, 91 U. S. 313, eited by the counsel for the State, the writ of mandamus was issued to promote, not to defeat, interstate transportation.

The question whether a statute which merely required interstate railroad trains, without going out of their course, to stop at county seats, would be within the constitutional power of the State, is not presented, and cannot be decided, upon this record.

The result is that the judgment of the Supreme Court of the State, which requires the Illinois Central Bailroad Company to cause its fast mail train to be brought into and stopped at its station in Cairo, is erroneous, and must be

Reversed, a/nd the cause remanded for further proceedings not inconsistent with this opinion.