Swift & Co. v. United States, 196 U.S. 375 (1905), was a case in which the United States Supreme Court ruled that the Commerce Clause allowed the federal government to regulate monopolies if it has a direct effect on commerce.

Together, they did $700 million a year in business and controlled half of the national market, and up to 75% in New York City.

When they were hit with federal injunctions in 1902, the Big Six agreed to merge into one National Packing Company in 1903 to continue to control the trade internally.

In this case, the chain ran from farm to retail store and crossed many state lines.

Public opinion, outraged by Upton Sinclair's novel The Jungle, which depicted horribly unsanitary conditions in Chicago's meatpacking plants, supported the decision.