Annotation 50 - Article I
The limitations imposed by this section were designed to prevent preferences as between ports because of their location in different States. They do not forbid such discriminations as between individual ports. Acting under the commerce clause, Congress may do many things that benefit particular ports and which incidentally result to the disadvantage of other ports in the same or neighboring States. It may establish ports of entry, erect and operate lighthouses, improve rivers and harbors, and provide structures for the convenient and economical handling of traffic. 1780 A rate order of the Interstate Commerce Commission which allowed an additional charge to be made for ferrying traffic across the Mississippi to cities on the east bank of the river was sustained over the objection that it gave an unconstitutional preference to ports in Texas. 1781 Although there were a few early intimations that this clause was applicable to the States as well as to Congress, 1782 the Supreme Court declared emphatically in 1886 that state legislation was unaffected by it. 1783 After more than a century, the Court confirmed, over the objection that this clause was offended, the power which the First Congress had exercised 1784 in sanctioning the continued supervision and regulation of pilots by the States. 1785
[Footnote 1780] Louisiana Pub. Serv. Comm. v. Texas & N.O.R. Co., 284 U.S. 125, 131 (1931); Pennsylvania v. Wheeling & Belmont Bridge Co., 59 U.S. (18 How.) 421, 433 (1856); South Carolina v. Georgia, 93 U.S. 4 (1876). In Williams v. United States, 255 U.S. 336 (1921) the argument that an act of Congress which prohibited interstate transportation of liquor into States whose laws prohibited manufacture or sale of liquor for beverage purposes was repugnant to this clause was rejected.
[Footnote 1784] 1 Stat. 53, 54, Sec. 4 (1789).