The U.S. Senate is a foundational institution of the American government, serving as the upper house of the bicameral United States Congress. Its composition and powers are established by Article One of the U.S. Constitution. The Senate's institutional history began on March 4, 1789, when the new government under the Constitution commenced. It was created by the framers at the Constitutional Convention of 1787 to solve the problem of representation between large and small states. The compromise ensured that while the House of Representatives would be based on population, the Senate would provide equal representation, with two Senators from each state, regardless of size. This design was intended to be a smaller, more deliberative body to counter the popular influence of the House.
Senators serve six-year terms. The mechanism for election changed with the 17th Amendment, ratified in 1913, which replaced election by state legislatures with direct election by the people. The Senate shares legislative power with the U.S. House of Representatives. However, the Senate holds unique powers, including the exclusive authority to approve or reject treaties and to confirm U.S. presidential appointments to executive and judicial offices. It also has the sole power to try impeachment cases brought by the House. This structure is a core component of the U.S. system of check and balance on the executive and judicial branches. The fundamental structure of two senators per state and the six-year term, as outlined in Article 1, Section 3 (as amended), has remained constant since the 17th Amendment.