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The Mountain Region
Mountain is one of the nine divisions the US Census Bureau uses beneath its four broad regions. It sits inside the West and contains eight states: Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah and Wyoming. They cover about 856,000 square miles of land and hold roughly 26 million people, which gives the division the lowest population density of the nine.
The 8 states in the Mountain division
| State | Capital | Admitted |
|---|---|---|
| Arizona | Phoenix | 1912 |
| Colorado | Denver | 1876 |
| Idaho | Boise | 1890 |
| Montana | Helena | 1889 |
| Nevada | Carson City | 1864 |
| New Mexico | Santa Fe | 1912 |
| Utah | Salt Lake City | 1896 |
| Wyoming | Cheyenne | 1890 |
The Mountain division is not the Mountain time zone
Two different things carry the name and they do not line up. The Mountain division is a Census grouping of eight whole states. The Mountain time zone is a clock boundary that cuts through counties. Nevada belongs to the Mountain division but keeps Pacific time, and Idaho is split, with the northern panhandle on Pacific time. Meanwhile El Paso in Texas, the western counties of Kansas, Nebraska, North Dakota and South Dakota, and Malheur County in Oregon all keep Mountain time without belonging to the division. Arizona is the sharpest case: it sits in the Mountain time zone but does not observe daylight saving, so for half the year its clocks read the same as California's.
Mountain is also not a fifth region. The four Census regions are Northeast, Midwest, South and West, and Mountain is a division one step below the West, alongside Pacific.
Population, area and economic weight
Arizona and Colorado between them hold roughly half the division's people. Wyoming, with fewer than 600,000 residents, is the least populous state in the country, while Arizona, Idaho and Utah have been among the fastest growing.
Six of the eight rank in the top ten states by size: Montana fourth, New Mexico fifth, Arizona sixth, Nevada seventh, Colorado eighth and Wyoming tenth. All eight are landlocked, the only Census division where that is true. Phoenix is the largest city here and one of the five largest in the United States. Arizona produces most of the country's copper, Wyoming leads the nation in coal, and New Mexico's share of the Permian Basin has made it one of the largest oil producing states.
What physically holds the eight states together
The Rocky Mountains run the length of the division from the Montana border with Canada down into New Mexico, and the Continental Divide follows them through Montana, Idaho, Wyoming, Colorado and New Mexico. Rain falling west of that line reaches the Pacific; rain east of it reaches the Gulf of Mexico.
West of the Rockies the land drops into the Great Basin, which covers most of Nevada and western Utah and drains nowhere at all, ending in the Great Salt Lake and salt flats. South of that, the Colorado Plateau carries the Grand Canyon, cut by the Colorado River across northern Arizona. Colorado has the highest mean elevation of any state, and Mount Elbert at 14,440 feet is both its high point and the tallest peak in the Rockies. Arizona, Colorado, New Mexico and Utah meet at the Four Corners, the only point in the country where four states touch, and all four are Mountain states.
How the Mountain states were settled
Santa Fe was founded in 1610 and is the oldest state capital in the country. Most of the division passed to the United States in 1848 under the Treaty of Guadalupe Hidalgo, with the southern strip of Arizona and New Mexico added by the Gadsden Purchase in 1853. Montana, Wyoming and eastern Colorado had come earlier, with the Louisiana Purchase.
Mormon pioneers entered the Salt Lake Valley in 1847 and laid down the settlement grid that still organizes Utah and southern Idaho. Mining supplied the rest: the Comstock Lode in Nevada from 1859, the Pike's Peak rush into Colorado from 1858, copper at Butte in Montana. Nevada was admitted in 1864, in the middle of the Civil War, which is why its flag reads Battle Born. Utah waited until 1896, after the Latter-day Saint church renounced plural marriage, and Arizona and New Mexico came in 1912 as the last two contiguous states ever admitted.
What the Mountain states are known for
Yellowstone, established in 1872 as the first national park anywhere in the world, lies mostly in Wyoming with corners in Montana and Idaho. Utah has five national parks of its own and hosted the Winter Olympics at Salt Lake City in 2002. The Navajo Nation, the largest Indian reservation in the United States, spans Arizona, New Mexico and Utah, and New Mexico has the highest Hispanic share of any state. Los Alamos, New Mexico, designed the first nuclear weapon, tested at Trinity in the southern desert in July 1945.
Where the division's edges are argued
Hardly anyone says Mountain states in conversation. People say Southwest for Arizona and New Mexico, and Rocky Mountain West for Colorado, Wyoming, Montana and Idaho. The Census bundles all eight into one division.
Nevada is the weakest fit: it runs on Pacific time, and its population sits in Las Vegas and Reno, both of which look toward California rather than Denver. New Mexico's Puebloan and Hispanic history has little in common with Montana's. Montana, Wyoming and Colorado each carry a slab of Great Plains east of the Rockies that resembles the Dakotas and Nebraska far more than it resembles Utah, but the Census assigns states whole, so those plains go into the West with the mountains.