| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Aurora | 1 | 415,462 | 386,688 | 1.32% | 2,531 | 164 | City |
| Thornton | 2 | 149,318 | 142,162 | 1.05% | 4,090 | 37 | City |
| Westminster | 3 | 116,095 | 116,639 | -0.07% | 3,672 | 32 | City |
| Commerce City | 4 | 74,414 | 62,760 | 2.86% | 2,016 | 37 | City |
| Brighton | 5 | 46,320 | 40,280 | 2.04% | 2,131 | 22 | City |
| Northglenn | 6 | 39,066 | 38,032 | 0.44% | 5,308 | 7 | City |
| Federal Heights | 7 | 14,011 | 14,393 | -0.45% | 7,894 | 2 | City |
| Lochbuie | 8 | 8,880 | 8,210 | 1.19% | 2,410 | 4 | Town |
| Bennett | 9 | 4,488 | 2,907 | 6.25% | 629 | 7 | Town |
| Mountain View | 10 | 512 | 539 | -0.97% | 5,505 | 0 | Town |
| Lakeside | 11 | 15 | 17 | -6.25% | 80 | 0 | Town |
Aurora is the largest city in Adams County, with a population of 415,462.
Lakeside is the smallest city in Adams County, with a population of 15.
There are 11 cities in Adams County, Colorado.