| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Castle Rock | 1 | 86,094 | 73,888 | 2.72% | 2,478 | 35 | Town |
| Parker | 2 | 67,604 | 58,737 | 2.45% | 3,012 | 22 | Town |
| Castle Pines | 3 | 16,557 | 11,207 | 6.25% | 1,726 | 10 | City |
| Larkspur | 4 | 222 | 205 | 1.37% | 140 | 2 | Town |
Castle Rock is the largest city in Douglas County, with a population of 86,094.
Larkspur is the smallest city in Douglas County, with a population of 222.
There are 4 cities in Douglas County, Colorado.