- William McKinley (January 29, 1843 – September 14, 1901) 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, Guam, and the Philippines; 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.