The United States Congress is the legislative branch of the federal government of the United States. It is a bicameral legislature, including a lower body, the U.S. House of Representatives, and an upper body, the U.S. Senate. They both meet in the United States Capitol in Washington, D.C.

Members of Congress are chosen through direct election, though vacancies in the Senate may be filled by a governor's appointment. Congress has a total of 535 voting members, a figure which includes 100 senators and 435 representatives; the House of Representatives has 6 additional non-voting members. The vice president of the United States, as President of the Senate, has a vote in the Senate only when there is a tie.

Congress convenes for a two-year term, commencing every other January. Elections are held every even-numbered year on Election Day. The members of the House of Representatives are elected for the two-year term of a Congress. The Reapportionment Act of 1929 established that there be 435 representatives, and the Uniform Congressional Redistricting Act requires that they be elected from single-member constituencies or districts. It is also required that the congressional districts be apportioned among states by population every ten years using the U.S. census results, provided that each state has at least one congressional representative.