<P> The composition and powers of the Senate are established by Article One of the United States Constitution . The Senate is composed of senators , each of whom represents a single state in its entirety , with each state being equally represented by two senators , regardless of its population , serving staggered terms of six years ; with fifty states presently in the Union , there are 100 U.S. Senators . From 1789 until 1913 , Senators were appointed by legislatures of the states they represented ; following the ratification of the Seventeenth Amendment in 1913 , they are now popularly elected . The Senate chamber is located in the north wing of the Capitol , in Washington , D.C. </P>
what determines the number of senate seats held by each state
Article One of the United States Constitution