26 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Aurora | Adams County | 407,211 |
| Arvada | Jefferson County | 121,250 |
| Alamosa | Alamosa County | 9,929 |
| Applewood | Jefferson County | 8,268 |
| Air Force Academy | El Paso County | 6,704 |
| Aspen | Pitkin County | 6,447 |
| Avon | Eagle County | 5,838 |
| Ault | Weld County | 2,845 |
| Acres Green | Douglas County | 2,663 |
| Aristocrat Ranchettes | Weld County | 2,487 |
| Akron | Washington County | 1,739 |
| Alamosa East | Alamosa County | 1,396 |
| Aetna Estates | Arapahoe County | 1,230 |
| Allenspark | Boulder County | 872 |
| Aspen Park | Jefferson County | 700 |
| Antonito | Conejos County | 616 |
| Altona | Boulder County | 537 |
| Aguilar | Las Animas County | 445 |
| Arboles | Archuleta County | 414 |
| Alma | Park County | 321 |
| Avondale | Pueblo County | 240 |
| Arriba | Lincoln County | 198 |
| Atwood | Logan County | 196 |
| Amherst | Phillips County | 97 |
| Alpine | Mineral County | 87 |
| Arapahoe | Cheyenne County | 50 |