| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lake Oswego | 1 | 39,495 | 40,876 | -0.57% | 3,647 | 11 | City |
| Oregon City | 2 | 38,298 | 37,780 | 0.32% | 3,811 | 10 | City |
| Happy Valley | 3 | 30,129 | 23,710 | 4.19% | 2,532 | 12 | City |
| Wilsonville | 4 | 28,119 | 26,712 | 1.03% | 3,724 | 8 | City |
| West Linn | 5 | 26,365 | 27,365 | -0.76% | 3,548 | 7 | City |
| Milwaukie | 6 | 22,214 | 21,174 | 0.45% | 4,457 | 5 | City |
| Canby | 7 | 17,952 | 18,213 | -0.29% | 3,821 | 5 | City |
| Sandy | 8 | 13,402 | 12,676 | 0.59% | 3,692 | 4 | City |
| Gladstone | 9 | 11,822 | 12,047 | -0.36% | 4,930 | 2 | City |
| Molalla | 10 | 10,075 | 10,230 | -0.29% | 4,063 | 2 | City |
| Estacada | 11 | 6,073 | 4,531 | 4.45% | 2,364 | 3 | City |
| Johnson City | 12 | 556 | 543 | 0.36% | 8,554 | 0 | City |
| Rivergrove | 13 | 533 | 545 | -0.56% | 3,081 | 0 | City |
| Barlow | 14 | 133 | 133 | -0.75% | 2,558 | 0 | City |
Lake Oswego is the largest city in Clackamas County, with a population of 39,495.
Barlow is the smallest city in Clackamas County, with a population of 133.
There are 14 cities in Clackamas County, Oregon.