Article I, Section 8, Clause 3:
[The Congress shall have Power . . . ] To regulate Commerce with foreign Nations, and among the several States, and with the Indian Tribes; . . .
The Commerce Clause gives Congress broad power to regulate interstate commerce and restricts states from impairing interstate commerce. Early Supreme Court cases primarily viewed the Commerce Clause as limiting state power rather than as a source of federal power. Of the approximately 1,400 Commerce Clause cases that the Supreme Court heard before 1900, most stemmed from state legislation.1 As a consequence, the Supreme Court’s early interpretations of the Commerce Clause focused on the meaning of “commerce” while paying less attention to the meaning of “regulate.” During the 1930s, however, the Supreme Court increasingly heard cases on Congress’s power to regulate commerce, with the result that its interstate Commerce Clause jurisprudence evolved markedly during the twentieth century.