14 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lake Oswego | 1 | 39,599 | 40,889 | -0.54% | 3,656 | 11 | City |
| Oregon City | 2 | 38,603 | 37,774 | 0.36% | 3,841 | 10 | City |
| Happy Valley | 3 | 31,404 | 24,098 | 4.03% | 2,639 | 12 | City |
| Wilsonville | 4 | 28,481 | 26,723 | 1.04% | 3,772 | 8 | City |
| West Linn | 5 | 26,209 | 27,373 | -0.73% | 3,527 | 7 | City |
| Milwaukie | 6 | 21,844 | 21,172 | 0.52% | 4,383 | 5 | City |
| Canby | 7 | 17,931 | 18,219 | -0.27% | 3,817 | 5 | City |
| Sandy | 8 | 13,154 | 12,661 | 0.63% | 3,624 | 4 | City |
| Gladstone | 9 | 11,824 | 12,046 | -0.31% | 4,931 | 2 | City |
| Molalla | 10 | 10,085 | 10,232 | -0.24% | 4,067 | 2 | City |
| Estacada | 11 | 6,117 | 4,538 | 4.49% | 2,381 | 3 | City |
| Johnson City | 12 | 558 | 543 | 0.54% | 8,585 | 0 | City |
| Rivergrove | 13 | 534 | 545 | -0.37% | 3,087 | 0 | City |
| Barlow | 14 | 144 | 134 | 1.41% | 2,769 | 0 | City |
Lake Oswego is the largest city in Clackamas County, with a population of 39,599.
Barlow is the smallest city in Clackamas County, with a population of 144.
There are 14 cities in Clackamas County, Oregon.