Founded on 1861-11-01, Boulder County is one of 64 counties in the state of Colorado. The city of Boulder is the county seat. With FIPS code of 13, Boulder County has a population of 329,543 and area of 740.48 square miles (1,918 km2).
List of all cities in Boulder County, CO alphabetically
| City/Town | Postal Code | Area Code |
| Allenspark, CO | 80510 | 303/720 |
| Boulder, CO | 80301 | 303/720 |
| 80302 | 303/720 | |
| 80303 | 303/720 | |
| 80304 | 303/720 | |
| 80305 | 303/720 | |
| 80306 | 303/720 | |
| 80307 | 303/720 | |
| 80308 | 303/720 | |
| 80309 | 303/720 | |
| 80310 | 303/720 | |
| 80314 | 303/720 | |
| 80321 | 303/720 | |
| 80322 | 303/720 | |
| 80323 | 303/720 | |
| 80328 | 303/720 | |
| 80329 | 303/720 | |
| Eldorado Springs, CO | 80025 | 303/720 |
| Erie, CO | 80516 | 303/720 |
| Frederick, CO | 80516 | 303/720 |
| Hygiene, CO | 80533 | 303/720 |
| I B M, CO | 80314 | 303/720 |
| Jamestown, CO | 80455 | 303/720 |
| Lafayette, CO | 80026 | 303/720 |
| Longmont, CO | 80501 | 303/720 |
| 80502 | 303/720 | |
| 80503 | 303/720 | |
| Louisville, CO | 80027 | 303/720 |
| 80028 | 303/720 | |
| Lyons, CO | 80540 | 303/720 |
| Nederland, CO | 80466 | 303/720 |
| Neodata, CO | 80322 | 303/720 |
| 80323 | 303/720 | |
| 80329 | 303/720 | |
| Neodata Business Reply, CO | 80321 | 303/720 |
| 80328 | 303/720 | |
| Niwot, CO | 80503 | 303/720 |
| 80544 | 303/720 | |
| Pinecliffe, CO | 80471 | 303/720 |
| Residence Halls University of Co, CO | 80310 | 303/720 |
| Storage Technology Corp, CO | 80028 | 303/720 |
| Superior, CO | 80027 | 303/720 |
| University of Colorado, CO | 80309 | 303/720 |
| Ward, CO | 80481 | 303/720 |
Map of Cities in Boulder County, CO
