who is given the power to admit new states
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, authorizes the Congress to admit new states into the United States beyond the thirteen already in existence at the time the Constitution went into effect.
United States Constitution Article Seven describes the process for establishing the proposed new frame of government. Anticipating that the influence of many state politicians would be Antifederalist, delegates to the Philadelphia Convention provided for ratification of the Constitution by popularly elected ratifying conventions in each state. The convention method also made it possible that judges, ministers and others ineligible to serve in state legislatures, could be elected to a convention. Suspecting that Rhode Island, at least, might not ratify, delegates decided that the Constitution would go into effect as soon as nine states (two-thirds rounded up) ratified.[53] Once ratified by this minimum number of states, it was anticipated that the proposed Constitution would become this Constitution between the nine or more that signed. It would not cover the four or fewer states that might not have signed.[54]