Arizona Desert
Arizona is the desert state of the United States. Three of America's four main deserts (the Sonoran, the Mojave and the Chihuahuan) all meet inside Arizona's borders. Add the dramatic Colorado Plateau in the north (home of the Grand Canyon) and the high "Sky Islands" mountain ranges of the south, and Arizona is one of the most varied desert landscapes anywhere in the world.
- CountryUnited StatesIn the southwest
- Deserts inside Arizona3Sonoran, Mojave, Chihuahuan
- Hottest tempapprox. 50 °CIn Phoenix in summer
- Highest peakHumphreys Peak3,851 m, Snowbowl ski area near Flagstaff
- Famous canyonThe Grand Canyon450 km long, 1.6 km deep
- Famous plantSaguaro cactusIconic of the Sonoran portion
Arizona's three deserts compared
The Sonoran is the dominant desert in Arizona, but parts of the smaller Mojave (in the northwest) and the Chihuahuan (in the southeast) also touch the state.
What are Arizona's deserts?
Arizona has so much variety in such a small area because it sits at the meeting point of several different geological and ecological regions.
- The Sonoran Desert covers most of southern Arizona, including the cities of Phoenix and Tucson. This is the area of saguaro cacti, palo verde trees and warm winters that most people think of as "Arizona".
- The Mojave Desert reaches into Arizona's northwest corner around Lake Mead and Hoover Dam.
- The Chihuahuan Desert reaches into the southeast around the city of Douglas and the famous Chiricahua Mountains.
- The Colorado Plateau in the north is technically not a desert (it gets too much rain) but is mostly dry high country with dramatic canyons and rock formations including the Grand Canyon, Monument Valley, and Antelope Canyon.
The Grand Canyon
The Grand Canyon in northern Arizona is one of the most famous landscapes on Earth. It is around 450 km long, up to 29 km wide, and over 1.6 km deep. The canyon was carved by the Colorado River cutting downward through the Colorado Plateau over the last 5 to 6 million years. The exposed rocks in the canyon walls record approx. 1.8 billion years of Earth's history, making the Grand Canyon one of the world's greatest natural geology classrooms.
Sky Islands
Southern Arizona has some of the best examples of Sky Islands in the world. These are isolated mountain ranges that rise high above the surrounding desert, with their cooler upper slopes covered in pine and oak forests. The Sky Islands include the Chiricahua, the Huachuca, the Santa Catalina, the Pinaleño and other ranges. Each is biologically a kind of island: animals and plants that need cooler conditions can survive on the mountain tops but cannot cross the desert between ranges. This isolation has produced many unique species found only on one or two Sky Islands.
Phoenix: a city in the desert
The capital of Arizona is Phoenix, one of the fastest-growing major cities in the United States. Phoenix sits in the heart of the Sonoran Desert and reaches temperatures of 50 °C in summer. The city depends almost entirely on water pumped from the Colorado River (over 540 km away) and from groundwater aquifers that are slowly being depleted. The sustainability of Phoenix in a warming climate is one of the great open questions of American urban planning.
Deeper dive: the Colorado Plateau, the Hopi and Navajo, and Phoenix water
The northern half of Arizona sits on the Colorado Plateau, a vast high-elevation region that also covers parts of Utah, Colorado and New Mexico. The plateau is made up of nearly horizontal sedimentary rock layers, mostly laid down between 250 and 65 million years ago in shallow seas, swamps, deserts and floodplains that successively covered the region. About 5 to 6 million years ago the entire plateau began rising, and the Colorado River and its tributaries cut deep canyons through the uplifted rock. The Grand Canyon is the most famous example but the plateau is full of dramatic rock formations: Bryce Canyon, Zion, Canyonlands, Mesa Verde, Monument Valley and others.
Northern Arizona is also home to several Native American nations. The Hopi have lived in their distinctive mesa-top villages for at least 1,000 years, making theirs some of the longest continuously inhabited settlements in North America. The much larger Navajo Nation (Diné) occupies a 70,000 square km reservation across northeastern Arizona, southeastern Utah and northwestern New Mexico, the largest Native American reservation in the United States. The Navajo were forced onto this land after the brutal "Long Walk" of 1864, when the US Army marched 8,000 Navajo people on a 480 km forced march to a camp in eastern New Mexico, where many died. The Navajo finally returned to a portion of their traditional homeland in 1868. The Navajo Nation is now a semi-sovereign government with its own laws, schools and police.
Phoenix depends almost entirely on the Central Arizona Project, a massive aqueduct system that lifts Colorado River water more than 870 metres in elevation over a 540 km journey from Lake Havasu to Phoenix and Tucson. The CAP delivers approx. 1.5 cubic km of water per year, more than half the water used in central Arizona. As Colorado River flows decline due to climate change and over-allocation, Arizona's share is being progressively cut: a 2022 declaration triggered the first ever cut to Arizona's allocation, and further reductions are expected. Long-term sustainability requires Phoenix to drastically reduce water use, find new sources, or both. Treatment and re-use of wastewater, capture of urban stormwater, and more efficient agriculture are all being attempted.
The country is the United States. Arizona's main desert is the Sonoran.