Colorado county map

Counties of a rectangular state

Colorado Territory organised 17 counties in 1861, and the pattern of growth since then follows the state’s economy: mining camps produced the small mountain counties (Clear Creek, Gilpin, Lake, San Juan, Summit), the ranching and dry-farming boom of the 1880s produced the large plains counties of the east (Kit Carson, Yuma, Baca, Prowers), and the sugar-beet and irrigation districts filled in the rest. Every county created after 1889 except Broomfield was carved from an existing one.

Denver has been a consolidated city and county since 1902. Broomfield became the second in 2001, assembled from parts of Adams, Boulder, Jefferson and Weld counties so that the fast-growing city would deal with one government instead of four. Both appear in the table as their own seat.

Spanish names dominate the south and the western slope: Alamosa, Animas, Conejos, Costilla, Huerfano, La Plata, Las Animas, Mesa, Montezuma, Rio Blanco, Rio Grande, Saguache, San Juan, San Miguel. The plains counties honour politicians and soldiers (Kit Carson, Sedgwick, Phillips, Logan, Morgan, Crowley). Arapahoe, Cheyenne, Kiowa, Ouray and Yuma record Native American nations and leaders.

All 64 counties of Colorado

Five county facts

• Largest by area: Las Animas County on the New Mexico line, about 4,770 square miles, seat Trinidad. Moffat and Weld are next.
• Smallest by area: Broomfield, about 33 square miles, followed by Denver at about 155 square miles. Among traditional counties, Gilpin (about 150 square miles) is the smallest.
• Most populous: Denver, about 715,000 people in 2020, narrowly ahead of El Paso County (Colorado Springs) at about 730,000 — in fact El Paso County passed Denver in the 2020 count. Arapahoe, Jefferson and Adams counties complete the top five; all are in the Front Range corridor.
• Least populous: San Juan County, seat Silverton, in the San Juan Mountains, with fewer than 1,000 people. Hinsdale and Mineral counties are the next smallest.
• Oldest and newest: the 17 counties of 1861 include Arapahoe, Boulder, El Paso, Jefferson, Larimer, Pueblo and Weld. Broomfield, created in 2001, is the newest county in the state and one of the newest in the country.

Reading the map

Press Streets and zoom in to follow the county lines. The eastern third of the state is a grid of large, nearly square plains counties. The Front Range counties from Larimer through Boulder, Jefferson, Denver, Arapahoe, Douglas and El Paso to Pueblo hold most of the population. West of the Continental Divide the counties follow river valleys: Mesa on the Colorado, Montrose and Delta on the Gunnison and Uncompahgre, La Plata on the Animas. Hinsdale County is one of the most remote in the lower 48, with a single paved road reaching Lake City. Colorado is entirely on Mountain Time.

Related maps

• Colorado map — cities, borders and geography.
• Blank Colorado map and printable Colorado map.
• Denver, the capital and largest city; Colorado Springs in El Paso County.
• Neighbouring county maps: Wyoming, Nebraska, Kansas, Oklahoma, New Mexico, Utah, Arizona.
• Mountain states · Rocky Mountain region · the West · Mountain Time Zone.
• Geography: Rocky Mountains, Continental Divide, Four Corners.
• All US county maps.