| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Arvada | 1 | 122,391 | 124,350 | -0.41% | 3,140 | 39 | City |
| Wheat Ridge | 2 | 32,007 | 32,380 | -0.23% | 3,425 | 9 | City |
| Golden | 3 | 20,341 | 20,394 | -0.24% | 2,111 | 10 | City |
| Superior | 4 | 13,750 | 13,106 | 0.83% | 3,496 | 4 | Town |
| Morrison | 5 | 362 | 397 | -0.55% | 220 | 2 | Town |
Arvada is the largest city in Jefferson County, with a population of 122,391.
Morrison is the smallest city in Jefferson County, with a population of 362.
There are 5 cities in Jefferson County, Colorado.