Admission to the Union

The Admission to the Union Clause of the United States Constitution, oftentimes called the New States Clause, and found at Article IV, Section 3, Clause 1, describes the authority vested in the United States Congress to admit new states into the United States beyond the thirteen already in existence at the time the Constitution went into effect. The Constitution went into effect on June 21, 1788, after ratification by 9 of the 13 states, and the federal government began operations under it on March 4, 1789. Since then, 37 additional states have been admitted into the Union.