16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Astoria | 1 | 9,835 | 10,185 | -0.72% | 1,610 | 6 | City |
| Astoria | 2 | 9,835 | 10,190 | -0.72% | 1,610 | 6 | City |
| Seaside | 3 | 7,093 | 7,160 | -0.24% | 1,752 | 4 | City |
| Seaside | 4 | 7,093 | 7,176 | -0.24% | 1,752 | 4 | City |
| Warrenton | 5 | 6,333 | 6,273 | 0.14% | 500 | 13 | City |
| Warrenton | 6 | 6,333 | 6,286 | 0.14% | 500 | 13 | City |
| Gearhart | 7 | 1,886 | 1,803 | 0.75% | 1,009 | 2 | City |
| Gearhart | 8 | 1,886 | 1,813 | 0.75% | 1,009 | 2 | City |
| Cannon Beach | 9 | 1,499 | 1,500 | -0.07% | 958 | 2 | City |
| Cannon Beach | 10 | 1,499 | 1,504 | -0.07% | 958 | 2 | City |
| Knappa | 11 | 1,181 | 1,033 | 7.17% | 572 | 2 | CDP |
| Svensen | 12 | 1,015 | 877 | 7.18% | 453 | 2 | CDP |
| Westport | 13 | 378 | 329 | 0.8% | 570 | 1 | CDP |
| River Point | 14 | 292 | 242 | 6.96% | 560 | 1 | CDP |
| Barnesdale | 15 | 231 | 188 | 6.94% | 310 | 1 | CDP |
| Jeffers Gardens | 16 | 146 | 312 | 7.35% | 258 | 1 | CDP |
Astoria is the largest city in Clatsop County, with a population of 9,835.
Jeffers Gardens is the smallest city in Clatsop County, with a population of 146.
There are 16 cities in Clatsop County, Oregon.