18 zips
| Zip Code | City | Population ↓ |
|---|---|---|
| 80501 | Longmont | 43,591 |
| 80503 | Longmont | 36,206 |
| 80027 | Louisville | 33,998 |
| 80026 | Lafayette | 32,549 |
| 80302 | Boulder | 29,751 |
| 80304 | Boulder | 25,634 |
| 80301 | Boulder | 25,252 |
| 80303 | Boulder | 24,934 |
| 80305 | Boulder | 16,101 |
| 80310 | Boulder | 7,530 |
| 80540 | Lyons | 4,620 |
| 80466 | Nederland | 3,469 |
| 80510 | Allenspark | 705 |
| 80481 | Ward | 477 |
| 80455 | Jamestown | 378 |
| 80025 | Eldorado Springs | 101 |
| 80471 | Pinecliffe | 0 |
| 80544 | Niwot | 0 |
The data shown reflect ZCTAs from the US Census. As of 2024, there are 18 ZCTAs in Boulder County, Colorado (US Census).