We elect a U.S. Senator for how many years?

U.S. Senators serve 6-YEAR terms. The Constitution sets this longer term so the Senate has more stability and continuity than the House. About one-third of Senate seats are up for election every 2 years, so the Senate is never entirely new — providing institutional memory. There is no term limit; senators can serve as long as they keep winning elections. The 17th Amendment (1913) changed the original system (where state legislatures chose senators) to direct popular election. Compare: House members serve 2-year terms (more responsive to voters but less stable); Presidents serve 4-year terms with a 2-term maximum (22nd Amendment); Federal judges including Supreme Court justices serve for life ('during good behavior').