Number One Observatory Circle, often referred to as the Naval Observatory, is the official residence of the vice president of the United States. Located on the northeast grounds of the U.S. Naval Observatory in Washington, D.C., the house was built in 1893 for the observatory superintendent. The chief of naval operations (CNO) liked the house so much that in 1923 he took over the house for himself. It remained the residence of the CNO until 1974, when Congress determined that it would be easier and less expensive to provide security in a government-provided residence, and authorized its transformation to the first official residence for the vice president, though a temporary one. It is still the "official temporary residence of the vice president of the United States" by law. The 1974 congressional authorization covered the cost of refurbishment and furnishing the house.

The vice president of the United States (VPOTUS) is the second-highest officer in the executive branch of the U.S. federal government, after the president of the United States, and ranks first in the presidential line of succession. The vice president is also an officer in the legislative branch, as the president of the Senate. In this capacity, the vice president is empowered to preside over the United States Senate, but may not vote except to cast a tie-breaking vote. The vice president is indirectly elected together with the president to a four-year term of office by the people of the United States through the Electoral College. Since the passage of the Twenty-fifth Amendment to the US Constitution, the vice president may also be appointed by the president to fill a vacancy, via majority confirmation by both the Senate and the House.