The United States Congress is the legislature of the federal government of the United States consisting of two houses: the Senate and the House of Representatives. The Congress meets in the Capitol in Washington, D.C.

Both senators and representatives are chosen through direct election, though vacancies in the Senate may be filled by a gubernatorial appointment. Members are usually affiliated to the Republican Party or to the Democratic Party, and only rarely to a third-party or as independents. Congress has 535 voting members: 435 Representatives and 100 Senators.

(Courtesy of Wikipedia)

Also see:

U.S. Senate

U.S. House of Representatives