Arizona (; Navajo: Hoozdo Hahoodzo [xòːztò xɑ̀xòːtsò]; O'odham: Alĭ ṣonak [ˡaɺi ˡʂonak]) is a U.S. 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. Its capital and largest city is Phoenix. Arizona is one of the Four Corners states. It has borders with New Mexico, Utah, Nevada, California, and Mexico, and one point in common with the southwestern corner of Colorado. Arizona's border with Mexico is 389 miles (626 km) long, on the northern border of the Mexican states of Sonora and Baja California.
Arizona is the 48th state and last of the contiguous states to be admitted to the Union, achieving statehood on February 14, 1912. Historically part of the territory of Alta California in New Spain, it became part of independent Mexico in 1821. After being defeated in the Mexican–American War, Mexico ceded much of this territory to the United States in 1848. The southernmost portion of the state was acquired in 1853 through the Gadsden Purchase.
Southern Arizona is known for its desert climate, with very hot summers and mild winters. Northern Arizona features forests of pine, Douglas fir, and spruce trees; the Colorado Plateau; some mountain ranges (such as the San Francisco Mountains); as well as large, deep canyons, with much more moderate summer temperatures and significant winter snowfalls. There are ski resorts in the areas of Flagstaff, Alpine, and Tucson. In addition to the Grand Canyon National Park, there are several national forests, national parks, and national monuments.
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. Although federal law gave all Native Americans the right to vote in 1924, Arizona excluded those living on reservations from voting until its state Supreme Court ruled in 1948 in favor of Native American plaintiffs.