Colorado is notable for its diverse geography, which includes alpine mountains, high plains, deserts with huge sand dunes, and deep canyons. In 1861, the United States Congress defined the boundaries of the new Territory of Colorado exclusively by lines of latitude and longitude, stretching from 37°N to 41°N latitude, and from 102°02'48"W to 109°02'48"W longitude (25°W to 32°W from the Washington Meridian). After 158 years of government surveys, the borders of Colorado are now officially defined by 697 boundary markers and 697 straight boundary lines. Colorado, Wyoming and Utah are the only states that have their borders defined solely by straight boundary lines with no natural features. The southwest corner of Colorado is the Four Corners Monument at 36°59'56"N, 109°2'43"W. This is the only place in the United States where four states meet: Colorado, New Mexico, Arizona, and Utah.
The summit of Mount Elbert at 14,440 feet (4,401.2 m) elevation in Lake County is the highest point in Colorado and the Rocky Mountains of North America. Colorado is the only U.S. state that lies entirely above 1,000 meters elevation. The point where the Arikaree River flows out of Yuma County, Colorado, and into Cheyenne County, Kansas, is the lowest point in Colorado at 3,317 feet (1,011 m) elevation. This point, which holds the distinction of being the highest low elevation point of any state, is higher than the high elevation points of 18 states and the District of Columbia.
A view of the arid high plains in Southeastern Colorado
A little less than half of Colorado is flat and rolling land. East of the Rocky Mountains are the Colorado Eastern Plains of the High Plains, the section of the Great Plains within Nebraska at elevations ranging from roughly 3,350 to 7,500 feet (1,020 to 2,290 m). The Colorado plains are mostly prairies but also include deciduous forests, buttes, and canyons. Precipitation averages 15 to 25 inches (380 to 640 mm) annually.
Eastern Colorado is presently mainly farmland and rangeland, along with small farming villages and towns. Corn, wheat, hay, soybeans, and oats are all typical crops. Most villages and towns in this region boast both a water tower and a grain elevator. Irrigation water is available from both surface and subterranean sources. Surface water sources include the South Platte, the Arkansas River, and a few other streams. Subterranean water is generally accessed through artesian wells. Heavy usage of these wells for irrigation purposes caused underground water reserves to decline in the region. Eastern Colorado also hosts a considerable amount and range of livestock, such as cattle ranches and hog farms.
Roughly 70% of Colorado's population resides along the eastern edge of the Rocky Mountains in the Front Range Urban Corridor between Cheyenne, Wyoming, and Pueblo, Colorado. This region is partially protected from prevailing storms that blow in from the Pacific Ocean region by the high Rockies in the middle of Colorado. The "Front Range" includes Denver, Boulder, Fort Collins, Loveland, Castle Rock, Colorado Springs, Pueblo, Greeley, and other townships and municipalities in between. On the other side of the Rockies, the significant population centers in Western Colorado (which is not considered the "Front Range") are the cities of Grand Junction, Durango, and Montrose.
The Continental Divide of the Americas extends along the crest of the Rocky Mountains. The area of Colorado to the west of the Continental Divide is called the Western Slope of Colorado. West of the Continental Divide, water flows to the southwest via the Colorado River and the Green River into the Gulf of California.
Within the interior of the Rocky Mountains are several large parks which are high broad basins. In the north, on the east side of the Continental Divide is the North Park of Colorado. The North Park is drained by the North Platte River, which flows north into Wyoming and Nebraska. Just to the south of North Park, but on the western side of the Continental Divide, is the Middle Park of Colorado, which is drained by the Colorado River. The South Park of Colorado is the region of the headwaters of the South Platte River.
In southmost Colorado is the large San Luis Valley, where the headwaters of the Rio Grande are located. The valley sits between the Sangre De Cristo Mountains and San Juan Mountains, and consists of large desert lands that eventually run into the mountains. The Rio Grande drains due south into New Mexico, Mexico, and Texas. Across the Sangre de Cristo Range to the east of the San Luis Valley lies the Wet Mountain Valley. These basins, particularly the San Luis Valley, lie along the Rio Grande Rift, a major geological formation of the Rocky Mountains, and its branches.
The high desert lands that make up the San Luis Valley in Southern Colorado
To the west of the Great Plains of Colorado rises the eastern slope of the Rocky Mountains. Notable peaks of the Rocky Mountains include Longs Peak, Mount Evans, Pikes Peak, and the Spanish Peaks near Walsenburg, in southern Colorado. This area drains to the east and the southeast, ultimately either via the Mississippi River or the Rio Grande into the Gulf of Mexico.
The Rocky Mountains within Colorado contain 53 peaks that are 14,000 feet (4,267 m) or higher in elevation above sea level, known as fourteeners. These mountains are largely covered with trees such as conifers and aspens up to the tree line, at an elevation of about 12,000 feet (3,658 m) in southern Colorado to about 10,500 feet (3,200 m) in northern Colorado. Above this tree line only alpine vegetation grows. Only small parts of the Colorado Rockies are snow-covered year round.
Much of the alpine snow melts by mid-August with the exception of a few snow-capped peaks and a few small glaciers. The Colorado Mineral Belt, stretching from the San Juan Mountains in the southwest to Boulder and Central City on the front range, contains most of the historic gold- and silver-mining districts of Colorado. Mount Elbert is the highest summit of the Rocky Mountains. The 30 highest major summits of the Rocky Mountains of North America all lie within the state.
Sandstone cliffs along the Colorado River north of Wolcott
Colorado Western Slope
The Grand Valley in Western Colorado, a large valley made up of high desert terrain. The city of Grand Junction is located in the heart of the valley
The Western Slope area of Colorado includes the western face of the Rocky Mountains and all of the state to the western border. This area includes several terrains and climates from alpine mountains to arid deserts. The Western Slope includes many ski resort towns in the Rocky Mountains and towns west of the mountains. It is less populous than the Front Range but includes a large number of national parks and monuments.
From west to east, the land of Colorado consists of desert lands, desert plateaus, alpine mountains, National Forests, relatively flat grasslands, scattered forests, buttes, and canyons in the western edge of the Great Plains. The famous Pikes Peak is located just west of Colorado Springs. Its isolated peak is visible from nearly the Kansas border on clear days, and also far to the north and the south. The northwestern corner of Colorado is a sparsely populated region, and it contains part of the noted Dinosaur National Monument, which is not only a paleontological area, but is also a scenic area of rocky hills, canyons, arid desert, and streambeds. Here, the Green River briefly crosses over into Colorado. Desert lands in Colorado are located in and around areas such as the Pueblo, Canon City, Florence, Great Sand Dunes National Park and Preserve, San Luis Valley, Cortez, Canyon of the Ancients National Monument, Hovenweep National Monument, Ute Mountain, Delta, Grand Junction, Colorado National Monument, and other areas surrounding the Uncompahgre Plateau and Uncompahgre National Forest.
The Western Slope of Colorado is drained by the Colorado River and its tributaries (primarily the Gunnison River, Green River, and the San Juan River), or by evaporation in its arid areas. The Colorado River flows through Glenwood Canyon, and then through an arid valley made up of desert from Rifle to Parachute, through the desert canyon of De Beque Canyon, and into the arid desert of Grand Valley, where the city of Grand Junction is located. Also prominent in or near the southern portion of the Western Slope are the Grand Mesa, which lies to the southeast of Grand Junction; the high San Juan Mountains, a rugged mountain range; and to the west of the San Juan Mountains, the Colorado Plateau, a high arid region that borders Southern Utah.
The Colorado National Monument near Grand Junction. The monument is made up of high desert canyons and sandstone rock formations.
Grand Junction, Colorado is the largest city on the Western Slope. Grand Junction and Durango are the only major centers of television broadcasting west of the Continental Divide in Colorado, though most mountain resort communities publish daily newspapers. Grand Junction is located along Interstate 70, the only major highway in Western Colorado. Grand Junction is also along the major railroad of the Western Slope, the Union Pacific. This railroad also provides the tracks for Amtrak's California Zephyr passenger train, which crosses the Rocky Mountains between Denver and Grand Junction via a route on which there are no continuous highways.
The Western Slope includes multiple notable destinations in the Colorado Rocky Mountains, including Glenwood Springs, with its resort hot springs, and the ski resorts of Aspen, Breckenridge, Vail, Crested Butte, Steamboat Springs, and Telluride.
Higher education in and near the Western Slope can be found at Colorado Mesa University in Grand Junction, Western Colorado University in Gunnison, Fort Lewis College in Durango, and Colorado Mountain College in Glenwood Springs and Steamboat Springs.
The Four Corners Monument in the southwest corner of Colorado marks the common boundary of Colorado, New Mexico, Arizona, and Utah; the only such place in the United States.