5 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Arvada | 1 | 120,628 | 124,363 | -0.51% | 3,095 | 39 | City |
| Wheat Ridge | 2 | 31,807 | 32,383 | -0.3% | 3,404 | 9 | City |
| Golden | 3 | 20,027 | 20,399 | -0.31% | 2,079 | 10 | City |
| Superior | 4 | 13,927 | 13,107 | 0.99% | 3,541 | 4 | Town |
| Morrison | 5 | 392 | 398 | -0.25% | 238 | 2 | Town |
Arvada is the largest city in Jefferson County, with a population of 120,628.
Morrison is the smallest city in Jefferson County, with a population of 392.
There are 5 cities in Jefferson County, Colorado.