The 39th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from March 4, 1865, to March 4, 1867, during Abraham Lincoln's final month as president, and the first two years of the administration of his successor, Andrew Johnson.

The 38th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the United States Senate and the United States House of Representatives. It met in Washington, D.C., from March 4, 1863, to March 4, 1865, during the last two years of President Abraham Lincoln's first term in office. The apportionment of seats in the House of Representatives was based on the 1860 United States census. The Senate had a Republican majority, and the House of Representatives had a Republican plurality.