11 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Aurora | 1 | 411,293 | 386,804 | 1% | 2,506 | 164 | City |
| Thornton | 2 | 148,938 | 142,191 | 0.76% | 4,080 | 37 | City |
| Westminster | 3 | 114,626 | 116,653 | -0.29% | 3,625 | 32 | City |
| Commerce City | 4 | 73,973 | 62,788 | 2.58% | 2,004 | 37 | City |
| Brighton | 5 | 45,062 | 40,294 | 1.8% | 2,073 | 22 | City |
| Northglenn | 6 | 38,410 | 38,040 | 0.16% | 5,219 | 7 | City |
| Federal Heights | 7 | 13,759 | 14,395 | -0.76% | 7,752 | 2 | City |
| Lochbuie | 8 | 8,792 | 8,213 | 1.12% | 2,386 | 4 | Town |
| Bennett | 9 | 4,421 | 2,906 | 6.07% | 619 | 7 | Town |
| Mountain View | 10 | 512 | 538 | -0.78% | 5,505 | 0 | Town |
| Lakeside | 11 | 14 | 16 | 0% | 74 | 0 | Town |
Aurora is the largest city in Adams County, with a population of 411,293.
Lakeside is the smallest city in Adams County, with a population of 14.
There are 11 cities in Adams County, Colorado.