We elect a US Senator for how many years?

Senators serve six-year terms. The Constitution sets the term length and staggers elections so that one-third of the Senate is up for election every two years. This staggered system means the Senate never turns over completely in a single election, providing institutional continuity. There is no constitutional limit on how many terms a Senator may serve, and many Senators have served for decades. By contrast, members of the House of Representatives serve two-year terms with all seats up for election simultaneously, and the President serves four-year terms with a two-term limit set by the 22nd Amendment. The longer Senate term was designed to give Senators more independence from immediate political pressure than House members.