The 64th United States Congress was a meeting of the legislative branch of the United States federal government, composed of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from March 4, 1915, to March 4, 1917, during the third and fourth years of Woodrow Wilson's presidency. The apportionment of seats in the House of Representatives was based on the 1910 United States census.

The 1914 United States Senate elections were held on November 3, 1914. These were the first regularly scheduled elections held following the ratification of the Seventeenth Amendment to the United States Constitution in 1913, which required that all seats up for election be popularly elected, rather than chosen by their state legislatures. Thus, it was the first time that elections were generally scheduled on Election Day to coincide with the U.S. House elections. The 32 seats of Class 3 were contested in regular elections in 1914. Special elections were also held to fill vacancies. These elections occurred in the middle of Democratic President Woodrow Wilson's first term.