4 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Castle Rock | 1 | 87,875 | 73,888 | 2.72% | 2,529 | 35 | Town |
| Parker | 2 | 68,783 | 58,853 | 2.47% | 3,064 | 22 | Town |
| Castle Pines | 3 | 17,136 | 11,213 | 6.11% | 1,786 | 10 | City |
| Larkspur | 4 | 230 | 208 | 1.77% | 145 | 2 | Town |
Castle Rock is the largest city in Douglas County, with a population of 87,875.
Larkspur is the smallest city in Douglas County, with a population of 230.
There are 4 cities in Douglas County, Colorado.