26 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Aurora | Adams County | 400,571 |
| Arvada | Jefferson County | 119,461 |
| Alamosa | Alamosa County | 9,928 |
| Applewood | Jefferson County | 8,191 |
| Air Force Academy | El Paso County | 6,661 |
| Aspen | Pitkin County | 6,355 |
| Avon | Eagle County | 5,834 |
| Ault | Weld County | 3,158 |
| Acres Green | Douglas County | 2,532 |
| Aristocrat Ranchettes | Weld County | 2,148 |
| Akron | Washington County | 1,776 |
| Aetna Estates | Arapahoe County | 1,284 |
| Alamosa East | Alamosa County | 1,284 |
| Aspen Park | Jefferson County | 1,037 |
| Allenspark | Boulder County | 646 |
| Antonito | Conejos County | 610 |
| Altona | Boulder County | 538 |
| Aguilar | Las Animas County | 445 |
| Arboles | Archuleta County | 409 |
| Alma | Park County | 323 |
| Avondale | Pueblo County | 305 |
| Alpine | Mineral County | 230 |
| Arriba | Lincoln County | 199 |
| Atwood | Logan County | 147 |
| Amherst | Phillips County | 96 |
| Arapahoe | Cheyenne County | 26 |