On April 7, 1789, the Senate created the position of doorkeeper and appointed James T. Mathers to the position. Over the years, the duties of the doorkeeper grew, and in 1798 the title of the office was changed to sergeant at arms and doorkeeper. Elected by the members of the Senate, the sergeant at arms serves as the protocol and chief law enforcement officer of the Senate and is the principal administrative manager for most support services. This role includes providing services to senators in their Washington, D.C., and state offices, to visitors, and to the Capitol complex. Senators have offices in their home states to maintain contact with their constituents. These offices rely on the sergeant at arms for lease negotiations, equipment, and technology.

The sergeant at arms also supervises the Senate pages, teenage messengers appointed and sponsored by senators from their state.