The State of Arizona ( ) is a state located in the southwestern region of the United States. The capital and largest city is Phoenix. The second largest city is Tucson, followed in size by the four Phoenix metropolitan area cities of Mesa, Glendale, Chandler, and Scottsdale.

Arizona was the 48th and last of the contiguous states admitted to the Union on February 14, 1912, the 50th anniversary of Arizona's recognition as a territory of the United States. Arizona is noted for its desert climate, exceptionally hot summers, and mild winters, but the high country in the north features pine forests and mountain ranges with cooler weather than the lower deserts. Population figures for the year ending July 1, 2006 indicate that Arizona was at that time the fastest growing state in the United States, exceeding the growth of the previous leader, Nevada, and is currently the second.

Arizona is one of the Four Corners states. It borders New Mexico, Utah, Nevada, California, touches Colorado, and has a international border with the states of Sonora and Baja California in Mexico. In addition to the Grand Canyon, many other national forests, parks, monuments, and Indian reservations are located in the state.

Geography

''See also lists of counties, rivers, lakes, state parks, National Parks and National Forests.

Arizona is located in the western United States as one of the Four Corners states. Arizona is the sixth largest state in area, after New Mexico and before Nevada. Of the state's , approximately 15% is privately owned. The remaining area is public forest and park land, recreation areas and Native American reservations.

Arizona is best known for its desert landscape, which is rich in xerophyte plants such as the cactus. It is also known for its climate, which presents exceptionally hot summers and mild winters. Less well known is the pine-covered high country of the Colorado Plateau in the north-central portion of the state, which contrasts with the desert Basin and Range region in the southern portions of the state.

Like other states of the Southwest, Arizona has an abundance of topographical characteristics in addition to its desert climate. Mountains and plateaus are found in more than half of the state. The largest stand in the world of Ponderosa pine trees is contained in Arizona. The Mogollon Rim, a escarpment, cuts across the central section of the state and marks the southwestern edge of the Colorado Plateau, where the state experienced its worst forest fire ever in 2002. Arizona belongs firmly within the Basin and Range region of North America. The region was shaped by prehistoric volcanism, followed by a cooling-off and related subsidence. The entire region is slowly sinking.

The Grand Canyon is a colorful, steep-sided gorge, carved by the Colorado River, in northern Arizona. The canyon is one of the seven natural wonders of the world and is largely contained in the Grand Canyon National Park—one of the first national parks in the United States. President Theodore Roosevelt was a major proponent of designating the Grand Canyon area, visiting on numerous occasions to hunt mountain lion and enjoy the scenery. The canyon was created by the Colorado River cutting a channel over millions of years, and is about long, ranges in width from 4 to nowrap: 18 miles (6 to 29 kilometers) and attains a depth of more than . Nearly 2 billion years of the Earth's history have been exposed as the Colorado River and its tributaries cut through layer after layer of sediment as the Colorado Plateaus have uplifted.