The Basin and Range Province stretches across roughly 300,000 square miles of the western United States and northwestern Mexico, running from southern Idaho down to the state of Sonora, Mexico, and from eastern California east to central Utah. It covers nearly the entire state of Nevada and reaches into parts of Oregon, Idaho, Utah, Arizona, New Mexico, Texas, and California.
States and Borders
Nevada sits at the heart of the province, with Basin and Range terrain covering almost the entire state. From there, the landscape extends into southwestern Oregon, southeastern Idaho, and western Utah to the north and east. To the south, it sweeps through large portions of Arizona and continues into New Mexico and far west Texas, where Big Bend National Park and the Guadalupe Mountains mark some of its easternmost outposts. Eastern California, including the Owens Valley and Death Valley, forms the western edge. South of the U.S. border, the province continues into the Mexican state of Sonora.
The region is bordered by distinctly different landscapes on all sides. The Sierra Nevada and Cascade Range wall it off to the west, the Colorado Plateau defines much of the eastern boundary in Utah and Arizona, and the Snake River Plain cuts across its northern limit in Idaho.
What Gives It That Shape
The name says it all: this is a landscape of alternating flat valleys (basins) and narrow mountain ranges, lined up in a roughly north-south pattern across hundreds of miles. The pattern was created by the Earth’s crust being pulled apart over millions of years. As the crust stretched, blocks of rock dropped down along steep faults to form valleys, while neighboring blocks were pushed upward to form ridges. Geologists call the dropped blocks “grabens” and the uplifted blocks “horsts.” The result looks, as one famous description puts it, like an army of caterpillars marching north.
This stretching has been going on for at least 12 million years in parts of northwestern Nevada and continues today. In one well-studied 140-mile-wide section of northwestern Nevada, the crust has been pulled apart by about 14 miles total, roughly a 12% stretch. The faulting that created these ranges progressed at a relatively steady rate for millions of years and is still active, which is why the region experiences earthquakes.
Extreme Elevation Differences
One of the most striking things about the Basin and Range is how dramatically the elevation changes over short distances. Death Valley, in eastern California, drops to about 100 feet below sea level, the lowest point in North America. Just 100 miles to the west, Mount Whitney in the Sierra Nevada reaches 14,505 feet, the highest point in the lower 48 states. The Owens Valley between them sits at 4,500 feet but is flanked on both sides by mountains topping 14,000 feet, making the valley floor nearly 10,000 feet below the surrounding peaks.
Within the Great Basin alone, the summits of 33 separate mountain ranges exceed about 9,800 feet. Over 100 relatively narrow mountain ranges cross the Great Basin, all running more or less north to south with dry basins between them.
The Great Basin: Its Largest Subregion
The Great Basin occupies the northern and central portion of the province and is the largest area of interior drainage in North America. That means no water that falls here ever reaches the ocean. Instead, streams collect runoff and groundwater and deliver it to lakes and dry lake beds called playas scattered across the basin floor. The Great Salt Lake in Utah is the most famous of these terminal lakes, but dozens of smaller ones dot the landscape.
The bowl-like shape created by the surrounding highlands traps all precipitation inside the region. Individual basins within the Great Basin form their own smaller drainage systems, each one a self-contained hydrological unit. This is why so much of the landscape is arid: water has no escape route and simply evaporates.
Notable Places Within the Province
Dozens of national parks and monuments sit within Basin and Range terrain, giving a sense of how geographically varied the province is. Death Valley National Park in California and Nevada occupies the province’s most extreme low point. Great Basin National Park in eastern Nevada protects high-elevation forests and ancient bristlecone pines. Saguaro National Park and Organ Pipe Cactus National Monument showcase the Sonoran Desert landscapes of southern Arizona. White Sands National Park in New Mexico features vast gypsum dune fields in a classic basin setting.
Further south, Big Bend National Park in Texas and the Guadalupe Mountains mark the province’s reach into the Chihuahuan Desert. Joshua Tree National Park in southern California, Zion National Park in Utah, and the Grand Canyon in Arizona all fall at least partially within Basin and Range boundaries. Lake Mead National Recreation Area straddles the Arizona-Nevada border in the middle of the province. The sheer number of protected sites across eight states reflects how large and geologically diverse this single province is.