26 cities
| City | County | 2026 Pop. ↓ |
|---|---|---|
| Aurora | Adams County | 411,293 |
| Arvada | Jefferson County | 120,628 |
| Alamosa | Alamosa County | 9,953 |
| Applewood | Jefferson County | 8,342 |
| Air Force Academy | El Paso County | 6,706 |
| Aspen | Pitkin County | 6,338 |
| Avon | Eagle County | 5,778 |
| Ault | Weld County | 3,030 |
| Acres Green | Douglas County | 2,640 |
| Aristocrat Ranchettes | Weld County | 2,564 |
| Akron | Washington County | 1,734 |
| Alamosa East | Alamosa County | 1,392 |
| Aetna Estates | Arapahoe County | 1,256 |
| Allenspark | Boulder County | 895 |
| Aspen Park | Jefferson County | 688 |
| Antonito | Conejos County | 611 |
| Altona | Boulder County | 539 |
| Aguilar | Las Animas County | 443 |
| Arboles | Archuleta County | 423 |
| Alma | Park County | 326 |
| Avondale | Pueblo County | 211 |
| Atwood | Logan County | 201 |
| Arriba | Lincoln County | 197 |
| Amherst | Phillips County | 103 |
| Alpine | Mineral County | 82 |
| Arapahoe | Cheyenne County | 53 |