The United States Senate is sometimes referred to as the "upper house" or "upper body," although there is no constitutional basis for these designations. The two chambers of the U.S. Congress were established as equal lawmaking bodies by the key framers of the Constitution. While equal in stature, each chamber has distinct duties and responsibilities.
The Senate and the House of Representatives (which is sometimes called the "lower house" or "lower body") comprise the legislative branch of the U.S. government. Historians believe that these inaccurate labels of "upper" for the Senate and "lower" for the House of Representatives stemmed from the fact that during the First Congress, the Senate occupied the second floor of Philadelphia's Congress Hall, which was a floor above the House of Representatives.