5 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Arvada | 1 | 121,250 | 124,363 | -0.51% | 3,111 | 39 | City |
| Wheat Ridge | 2 | 31,903 | 32,383 | -0.3% | 3,414 | 9 | City |
| Golden | 3 | 20,089 | 20,399 | -0.31% | 2,085 | 10 | City |
| Superior | 4 | 13,790 | 13,107 | 1% | 3,506 | 4 | Town |
| Morrison | 5 | 393 | 398 | -0.25% | 239 | 2 | Town |
Arvada is the largest city in Jefferson County, with a population of 121,250.
Morrison is the smallest city in Jefferson County, with a population of 393.
There are 5 cities in Jefferson County, Colorado.