Colorado — All 64 Counties
Colorado has 64 counties with 479 communities and a combined population of 5,047,527.
| County | Towns | Population |
| Adams County | 20 | 1,019,457 |
| Denver County | 1 | 713,734 |
| El Paso County | 20 | 653,685 |
| Larimer County | 10 | 340,626 |
| Boulder County | 33 | 327,091 |
| Douglas County | 22 | 322,666 |
| Jefferson County | 19 | 322,527 |
| Arapahoe County | 22 | 296,742 |
| Weld County | 24 | 228,010 |
| Pueblo County | 10 | 151,579 |
| Mesa County | 10 | 128,572 |
| Broomfield County | 1 | 75,110 |
| Eagle County | 12 | 47,682 |
| Garfield County | 13 | 44,423 |
| Fremont County | 11 | 35,243 |
| Montrose County | 5 | 24,050 |
| La Plata County | 5 | 23,591 |
| Morgan County | 13 | 20,219 |
| Delta County | 7 | 18,038 |
| Routt County | 5 | 16,744 |
| Summit County | 9 | 16,209 |
| Logan County | 8 | 15,015 |
| Otero County | 8 | 13,884 |
| Montezuma County | 5 | 12,268 |
| Alamosa County | 3 | 11,419 |
| Chaffee County | 8 | 10,221 |
| Pitkin County | 5 | 10,190 |
| Las Animas County | 14 | 9,745 |
| Teller County | 7 | 9,727 |
| Moffat County | 3 | 9,674 |
| Gunnison County | 6 | 9,340 |
| Prowers County | 5 | 9,164 |
| Rio Grande County | 6 | 9,139 |
| Clear Creek County | 14 | 8,946 |
| Grand County | 8 | 8,102 |
| Elbert County | 6 | 6,700 |
| Yuma County | 8 | 6,320 |
| San Miguel County | 6 | 5,357 |
| Rio Blanco County | 2 | 5,100 |
| Kit Carson County | 6 | 5,082 |
| Lake County | 3 | 4,608 |
| Conejos County | 7 | 3,906 |
| Huerfano County | 3 | 3,889 |
| Phillips County | 4 | 3,484 |
| Ouray County | 5 | 3,129 |
| Crowley County | 4 | 3,019 |
| Lincoln County | 4 | 2,945 |
| Bent County | 3 | 2,648 |
| Baca County | 6 | 2,327 |
| Washington County | 3 | 2,318 |
| Archuleta County | 2 | 2,114 |
| Sedgwick County | 3 | 1,725 |
| Costilla County | 4 | 1,357 |
| Custer County | 2 | 1,242 |
| Cheyenne County | 3 | 1,202 |
| Park County | 4 | 1,122 |
| Dolores County | 2 | 1,072 |
| Kiowa County | 5 | 797 |
| Jackson County | 1 | 658 |
| Saguache County | 4 | 654 |
| San Juan County | 1 | 613 |
| Hinsdale County | 3 | 550 |
| Gilpin County | 2 | 450 |
| Mineral County | 1 | 307 |