The Tariff Act of 1890, commonly called the McKinley Tariff, was an act of the United States Congress, framed by then Representative William McKinley, that became law on October 1, 1890. The tariff raised the average duty on imports to almost 50%, an increase designed to protect domestic industries and workers from foreign competition, as promised in the Republican platform. It represented protectionism, a policy supported by Republicans and denounced by Democrats. It was a major topic of fierce debate in the 1890 Congressional elections, which gave a Democratic landslide.

William McKinley was an American politician who served as the 25th president of the United States from 1897 until his assassination in 1901. A member of the Republican Party, he led a realignment that made Republicans largely dominant in the industrial states and nationwide for decades. He presided over victory in the Spanish–American War of 1898; gained control of Hawaii, Puerto Rico, the Philippines and Cuba; restored prosperity after a deep depression; rejected the inflationary monetary policy of free silver, keeping the nation on the gold standard; and raised protective tariffs.