8 states · Census division · 24,919,150 people · 863,565 sq mi
Mountain states map
The Mountain division is the eight interior western states: Montana, Idaho, Wyoming, Colorado, Utah, Nevada, Arizona and New Mexico. It is the largest division by area in the contiguous US and the emptiest.
How the region is defined
The Mountain division is the inland half of the Census West region. Its eight states — Montana, Idaho, Wyoming, Colorado, Utah, Nevada, Arizona and New Mexico — form a block bounded by Canada, the Great Plains states, Mexico and the three Pacific coast states. The name is a Census label; the informal Rocky Mountain states usually leave out Nevada and Arizona, which are desert rather than Rockies, and the Southwest usually takes Arizona and New Mexico.
The eight states had 24,919,150 people in 2020 on 863,565 square miles — 23% of the country's land with 8% of its people. Arizona and Colorado hold more than half the population; Wyoming (576,851) and Montana (1,084,225) are two of the three least populous states. Phoenix (1,608,139) is the fifth-largest US city and the largest state capital.
States, capitals and largest cities
| State | Capital | Largest city | Population (2020) | Area (sq mi) |
|---|---|---|---|---|
| Arizona (AZ) | Phoenix | Phoenix | 7,151,502 | 113,990 |
| Colorado (CO) | Denver | Denver | 5,773,714 | 104,094 |
| Idaho (ID) | Boise | Boise | 1,839,106 | 83,569 |
| Montana (MT) | Helena | Billings | 1,084,225 | 147,040 |
| Nevada (NV) | Carson City | Las Vegas | 3,104,614 | 110,572 |
| New Mexico (NM) | Santa Fe | Albuquerque | 2,117,522 | 121,590 |
| Utah (UT) | Salt Lake City | Salt Lake City | 3,271,616 | 84,897 |
| Wyoming (WY) | Cheyenne | Cheyenne | 576,851 | 97,813 |
| Total (8 states) | 24,919,150 | 863,565 |
Geography
The Rocky Mountains enter from Canada through Montana and Idaho, widen through Wyoming and reach their greatest height in Colorado, where Mount Elbert (14,440 ft) is the highest summit in the Rockies and the division. The Continental Divide follows the crest through Montana, Wyoming, Colorado and New Mexico. Yellowstone, the first national park, sits on a volcanic plateau in the north-west corner of Wyoming.
West and south of the Rockies are three plateaus and basins. The Colorado Plateau covers the Four Corners of Utah, Colorado, New Mexico and Arizona and is cut by the Grand Canyon. The Great Basin covers almost all of Nevada and western Utah, a region of parallel ranges and valleys with no drainage to the ocean; the Great Salt Lake is its largest remnant lake. The Snake River Plain crosses southern Idaho. South of all of these are the Mojave, Sonoran and Chihuahuan deserts.
The Colorado River rises in Colorado, crosses Utah and Arizona, forms the Nevada–Arizona border at Hoover Dam and leaves for California and Mexico. The Rio Grande rises in Colorado and runs the length of New Mexico. The Snake drains Idaho to the Columbia; the Missouri begins at Three Forks, Montana. All eight states are on Mountain time except Nevada (Pacific) and northern Idaho (Pacific); Arizona does not observe daylight saving.
Related maps
- Parent region: West; sibling division Pacific.
- Overlapping informal regions: Rocky Mountain states, Southwest, Great Plains.
- Quiz: Western states quiz.
- Cities: Phoenix, Denver, Las Vegas, Albuquerque, Salt Lake City, Boise.
- Geography: Rocky Mountains, Four Corners, Deserts, State high points.