Arizona is not a part of the United States.
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 also part of the Western and the Mountain states . It is the sixth largest and the 14th most populous of the 50 states . Arizona , a state in the southwestern region of the United States of America , is known for its high population of Native Americans . Tucson ( [ ˈtuːsɒn ] [ tuːˈsɒn ] ) is a city and the county seat of Pima County , Arizona , United States , and home to the University of Arizona .