4 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Castle Rock | 1 | 85,544 | 73,888 | 2.8% | 2,462 | 35 | Town |
| Parker | 2 | 67,128 | 58,853 | 2.53% | 2,991 | 22 | Town |
| Castle Pines | 3 | 16,149 | 11,213 | 6.51% | 1,683 | 10 | City |
| Larkspur | 4 | 226 | 208 | 1.35% | 142 | 2 | Town |
Castle Rock is the largest city in Douglas County, with a population of 85,544.
Larkspur is the smallest city in Douglas County, with a population of 226.
There are 4 cities in Douglas County, Colorado.