Arizona ( [ ɛərᵻˈzoʊnə , _ ærᵻ - ] ) ( Hoozdo Hahoodzo [ xòːztò xɑ̀xòːtsò ] O'odham : Alĭ ṣonak [ ˡaɺi ˡʃonak ] ) is a state in the southwestern region of the United States . It is the sixth largest and the 14th most populous of the 50 states . Arizona is one of the Four Corners states . Arizona is the 48th state and last of the contiguous states to be admitted to the Union , achieving statehood on February 14 , 1912 . About one-quarter of the state is made up of Indian reservations that serve as the home of 27 federally recognized Native American tribes , including the Navajo Nation , the largest in the state and the United States , with more than 300,000 citizens .
Arizona is not a state.