Political divisions of the United States or administrative divisions of the United States are the various governing entities that together form the United States. The first subdivision of the United States, meaning the union of states, is the state. The admission of sovereign states into the United States, i.e., the union of states, beyond the original thirteen states, is authorized under Article IV, Section 3, of the Constitution for the United States of America. Most of the states admitted to the union after the original 13 have been formed within territories of the United States (that is, land under the sovereignty of the federal government but not part of any state) that were organized by an act or resolution of the United States Congress, subject to the Congress' plenary powers under