In September 1901, William McKinley was at the height of his power as president. Elected in 1896, during the serious economic depression resulting from the Panic of 1893, he had defeated his Democratic rival, William Jennings Bryan. McKinley led the nation both to a return to prosperity and to victory in the Spanish–American War in 1898, taking possession of such Spanish colonies as Puerto Rico and the Philippines. Re-elected handily in a rematch against Bryan in 1900, according to historical writer Eric Rauchway, "it looked as if the McKinley Administration would continue peaceably unbroken for another four years, a government devoted to prosperity".
McKinley's original vice president, Garret Hobart, had died in 1899, and McKinley left the choice of a running mate to the 1900 Republican National Convention. In advance of the convention, New York's Republican political boss, Senator Thomas C. Platt, saw an opportunity to politically sideline his state's governor, former Assistant Secretary of the Navy Theodore Roosevelt, by pushing for his nomination as vice president. Roosevelt accepted the nomination and was elected on McKinley's ticket.
Leon Czolgosz was born in Detroit, Michigan, in 1873, the son of Polish immigrants. The Czolgosz family moved several times as Paul Czolgosz, Leon's father, sought work throughout the Midwest. As an adult, Leon Czolgosz worked in a Cleveland factory until he lost his job in a labor dispute in 1893. Thereafter, he worked irregularly and attended political and religious meetings, trying to understand the reasons for the economic turmoil of the Panic of 1893. In doing so, he became interested in anarchism. By 1901, this movement was feared in the United States — New York's highest court had ruled that the act of identifying oneself as an anarchist in front of an audience was a breach of the peace. Anarchists had taken a toll in Europe by assassinating or attempting assassinations of a half-dozen officials and members of royal houses, and had been blamed for the 1886 Haymarket bombing in Chicago.
Two American presidents had been assassinated in the 19th century—Abraham Lincoln in 1865 and James A. Garfield in 1881. Even considering this history, McKinley did not like security personnel to come between him and the people. When in his hometown, Canton, Ohio, he often walked to church or the business district without protection, and in Washington went on drives with his wife without any guard in the carriage.