page_title: Southwestern United States
section_title: Regional geography
hierarchical_section_title: Southwestern United States / Regional geography
caption_attribution_description: English: Four Corners Monument April 2007 by David Jolley
context_page_description: The Southwestern United States, also known as the American Southwest, Desert Southwest, or simply the Southwest, is the informal name for a region of the western United States. Definitions of the region's boundaries vary a great deal and have never been standardized, though many boundaries have been proposed. For example, one definition includes the stretch from the Mojave Desert in California to Carlsbad, New Mexico, and from the Mexico–United States border to the southern areas of Colorado, Utah, and Nevada. The largest metropolitan areas are centered around Phoenix, Las Vegas, Tucson, Albuquerque, and El Paso. Those five metropolitan areas have an estimated total population of more than 9.6 million as of 2017, with nearly 60 percent of them living in the two Arizona cities—Phoenix and Tucson.
  Most of the area was part of the Viceroyalty of New Spain in the Spanish Empire before becoming part of Mexico. European settlement was almost non-existent outside New Mexico in 1848, when it became part of the United States through the Treaty of Guadalupe Hidalgo, while southern areas of Arizona and southwestern New Mexico were added in the later Gadsden Purchase.
context_section_description: The geography of the region is mainly made up by four features: the Mojave, Sonoran, and Chihuahuan Deserts, and the Colorado Plateau; although there are other geographical features as well, such as a portion of the Great Basin Desert. The deserts dominate the southern and western reaches of the area, while the plateau (which is largely made up of high desert) is the main feature north of the Mogollon Rim. The two major rivers of the region are the Colorado River, running in the northern and western areas, and the Rio Grande, running in the east, north to south.
  Formed approximately 8000 years ago, the Chihuahuan Desert is a relatively dry desert, although it is slightly wetter than the Sonoran Desert to the west. The Chihuahuan Desert spreads across the southeastern portion of the region, covering from southeastern Arizona, across southern New Mexico, and the portion of Texas included in the Southwest. While it is the second largest desert in the United States, only a third of the desert is within the United States, with the rest in Mexico. El Paso and Albuquerque are the major US cities in this desert, with other smaller cities being Las Cruces and Roswell in New Mexico and Willcox in Arizona.
  The elevation in the Chihuahuan varies from about 1,750 to 6,000 feet, as there are several larger mountain ranges, such as the Organ Mountains, the Guadalupe Mountains, and the Chiracahua Mountains, plus many smaller mountain ranges contained in the area, namely the San Andres and Doña Anas in New Mexico, the Franklin Mountains and the Davis Mountains. The Chihuahuan is a "rain shadow" desert, formed between two mountain ranges (the Sierra Madre Occidental on the west and the Sierra Madre Oriental on the east) which block oceanic precipitation from reaching the area. The Chihuahuan Desert is considered the "most biologically diverse desert in the Western Hemisphere and one of the most diverse in the world", and includes more species of cacti than any other desert in the world. The most prolific plants in this region are agave, yucca and creosote bushes, in addition to the ubiquitous presence of various cacti species.
  When people think of the desert southwest, the landscape of the Sonoran Desert is what mostly comes to mind. The Sonoran Desert makes up the southwestern portion of the Southwest; most of the desert lies in Mexico, but its United States component lies on the southeastern border of California, and the western 2/3 of southern Arizona. Rainfall averages between 4–12 inches per year, and the desert's most widely known inhabitant is the saguaro cactus, which is unique to the desert. It is bounded on the northwest by the Mojave Desert, to the north by the Colorado Plateau and to the east by the Arizona Mountains forests and the Chihuahuan Desert. Aside from the trademark saguaro, the desert has the most diverse plant life of any desert in the world, and includes many other species of cacti, including the organ-pipe, senita, prickly pear, barrel, fishhook, hedgehog, cholla, silver dollar, and jojoba. The portion of the Sonora Desert which lies in the Southwestern United States is the most populated area within the region. Six of the top ten major population centers of the region are found within its borders: Phoenix, Tucson, Mesa, Chandler, Glendale, and Scottsdale, all in Arizona. Also within its borders are Yuma and Prescott Arizona.
  The most northwest portion of the American Southwest is covered by the Mojave Desert. Bordered on the south by the Sonoran Desert and the east by the Colorado Plateau, its range within the region makes up the southeast tip of Nevada, and the northwestern corner of Arizona. In terms of topography, the Mojave is very similar to the Great Basin Desert, which lies just to its north. Within the region, Las Vegas is the most populous city; other significant areas of human habitation include Laughlin and Pahrump in Nevada, and Lake Havasu City, Kingman, and Bullhead City in Arizona. The Mojave is the smallest, driest and hottest desert within the United States. The Mojave gets less than six inches 
caption: Four Corners Monument
exif: {"Image Make": "EASTMAN KODAK COMPANY", "Image Model": "KODAK C310 DIGITAL CAMERA", "Image XResolution": "230", "Image YResolution": "230", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 3.0", "Image DateTime": "2007:04:16 12:15:02", "Image YCbCrPositioning": "Co-sited", "Image ExifOffset": "236", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail Orientation": "Horizontal (normal)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "4802", "Thumbnail JPEGInterchangeFormatLength": "2664", "EXIF ExposureTime": "21/31250", "EXIF FNumber": "9/2", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "100", "EXIF ExifVersion": "0221", "EXIF DateTimeOriginal": "2007:04:14 12:11:36", "EXIF DateTimeDigitized": "2007:04:14 12:11:36", "EXIF ComponentsConfiguration": "YCbCr", "EXIF CompressedBitsPerPixel": "16/5", "EXIF ShutterSpeedValue": "1053/100", "EXIF ApertureValue": "433/100", "EXIF ExposureBiasValue": "0", "EXIF MaxApertureValue": "433/100", "EXIF MeteringMode": "CenterWeightedAverage", "EXIF Flash": "Flash did not fire, auto mode", "EXIF FocalLength": "59/10", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2304", "EXIF ExifImageLength": "1728", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "4650", "EXIF ExposureIndex": "100", "EXIF SensingMethod": "One-chip color area", "EXIF FileSource": "Digital Camera", "EXIF SceneType": "Directly Photographed", "EXIF CustomRendered": "Custom", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF DigitalZoomRatio": "0", "EXIF FocalLengthIn35mmFilm": "36", "EXIF SceneCaptureType": "Standard", "EXIF GainControl": "None", "EXIF Contrast": "Normal", "EXIF Saturation": "Normal", "EXIF Sharpness": "Normal", "EXIF SubjectDistanceRange": "0"}