The 10th United States Congress was a meeting of the legislative branch of the United States federal government, consisting of the Senate and the House of Representatives. It met in Washington, D.C., from March 4, 1807, to March 4, 1809, during the seventh and eighth years of Thomas Jefferson's presidency. The apportionment of seats in the House of Representatives was based on the 1800 census; both chambers had an overwhelming Democratic-Republican majority.

The Republican Party, retroactively called the Democratic-Republican Party, and also referred to as the Jeffersonian Republican Party among other names, was an American political party founded by Thomas Jefferson and James Madison in the early 1790s that championed liberalism, republicanism, individual liberty, equal rights, decentralization, free markets, free trade, agrarianism, and sympathy with the French Revolution. The party became increasingly dominant after the 1800 elections as the opposing Federalist Party collapsed.