How long is a term for a U.S. Senator?

The Framers created staggered Senate terms so that only one-third of senators face election every two years, ensuring the Senate never experiences complete turnover. This structure was intended to make the Senate a more deliberative body than the House, with members less directly swayed by immediate public opinion. Originally, state legislatures elected senators; since the 17th Amendment in 1913, voters elect them directly.