In the U.S., any commercial transaction or traffic that crosses state boundaries or that involves more than one state.
Government regulation of interstate commerce is founded on the commerce clause of the Constitution (Article I, section 8), which authorizes Congress "To regulate Commerce with foreign Nations, and among the several States, and with Indian Tribes." The Interstate Commerce Commission , established in 1887, was originally intended to regulate the railroad industry; its jurisdiction was later expanded to include trucks, ships, freight forwarders, and other interstate carriers. The Sherman Act (1890), followed by the Clayton Act (1914), made illegal any act that tended to interfere with free competition between and among industries, businesses, and any interstate commercial venture. The Federal Trade Commission (FTC) was established by the Federal Trade Commission Act of 1914, which gave the FTC powers
judicial, legislative, and executive
to administer the Sherman and Clayton acts. The Federal Communications Commission (FCC) was created to protect the right of the public to the airwaves through licensing and oversight of the practices of broadcasters in radio and television. In the 20th century, court decisions tended to interpret interstate commerce broadly, thus allowing Congress to regulate a wide variety of activities by which interstate commerce could be affected, even if they took place within the borders of a single state. One such decision was Heart of Atlanta Motel v. U.S. (1964), in which the Supreme Court upheld the prohibition of discrimination in public accommodations contained in the 1964 Civil Rights Act on the ground that the discriminatory practices of a business operating in only one state could affect interstate commerce.