11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Aurora | 1 | 407,211 | 386,804 | 1.01% | 2,481 | 164 | City |
| Thornton | 2 | 147,813 | 142,191 | 0.77% | 4,049 | 37 | City |
| Westminster | 3 | 114,964 | 116,653 | -0.29% | 3,636 | 32 | City |
| Commerce City | 4 | 72,109 | 62,788 | 2.65% | 1,954 | 37 | City |
| Brighton | 5 | 44,267 | 40,294 | 1.83% | 2,036 | 22 | City |
| Northglenn | 6 | 38,348 | 38,040 | 0.16% | 5,210 | 7 | City |
| Federal Heights | 7 | 13,865 | 14,395 | -0.76% | 7,811 | 2 | City |
| Lochbuie | 8 | 8,695 | 8,213 | 1.12% | 2,360 | 4 | Town |
| Bennett | 9 | 4,168 | 2,906 | 6.44% | 584 | 7 | Town |
| Mountain View | 10 | 516 | 538 | -0.96% | 5,548 | 0 | Town |
| Lakeside | 11 | 14 | 16 | -6.67% | 74 | 0 | Town |
Aurora is the largest city in Adams County, with a population of 407,211.
Lakeside is the smallest city in Adams County, with a population of 14.
There are 11 cities in Adams County, Colorado.