American citizens that are registered voters directly elect the United States Congress. Congressional elections, referred to as mid-term elections, are held once every 2 years through a U.S. President's term of office.
Congress is comprised of an upper house called the Senate and a lower chamber called the House of Representatives or simply the House. This bicameral system forms the legislative branch of the U.S. government. Congressmen are responsible for the creation of federal statutory laws.
Each of the 50 states are represented by two U.S. Senators. The number of House Representatives varies according to the size of the population of a state. Apportionment refers to the process wherein a state is divided into several congressional districts. Each district elects one representative. The number of the members of the lower house has remained at 435 since it was set by law in 1911.
During mid-term elections in November, one-third of all 100 Senators and all 435 members of the House are eligible for re-election. Primary elections are held in most states to determine which congressional candidates will be on the final mid-term elections ballot.
All registered American voters or the electorate are eligible to elect the Congress. The result is often used as an indicator of the people's satisfaction or frustration regarding the U.S. President's performance.