25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 181,513 | 175,977 | 0.61% | 3,710 | 49 | City |
| Keizer | 2 | 39,108 | 39,325 | -0.11% | 5,443 | 7 | City |
| Woodburn | 3 | 31,544 | 26,068 | 3.6% | 5,384 | 6 | City |
| Hayesville | 4 | 22,294 | 22,189 | 0.71% | 7,456 | 3 | CDP |
| Four Corners | 5 | 16,217 | 16,491 | 0.11% | 6,635 | 2 | CDP |
| Silverton | 6 | 10,367 | 10,487 | -0.23% | 2,956 | 4 | City |
| Stayton | 7 | 8,591 | 8,238 | 0.82% | 2,751 | 3 | City |
| Aumsville | 8 | 4,207 | 4,252 | -0.21% | 3,726 | 1 | City |
| Mount Angel | 9 | 3,450 | 3,379 | 0.41% | 3,037 | 1 | City |
| Hubbard | 10 | 3,394 | 3,433 | -0.24% | 4,232 | 1 | City |
| Jefferson | 11 | 3,287 | 3,329 | -0.27% | 3,835 | 1 | City |
| Sublimity | 12 | 2,857 | 2,967 | -0.76% | 3,046 | 1 | City |
| Gervais | 13 | 2,564 | 2,598 | -0.27% | 6,300 | 0 | City |
| Turner | 14 | 2,405 | 2,450 | -0.37% | 1,678 | 1 | City |
| Aurora | 15 | 1,117 | 1,142 | -0.45% | 2,308 | 0 | City |
| Donald | 16 | 1,014 | 1,009 | 0.1% | 2,675 | 0 | City |
| Mehama | 17 | 594 | 396 | 3.48% | 1,297 | 0 | CDP |
| Labish Village | 18 | 517 | 491 | 1.37% | 9,574 | 0 | CDP |
| Gates | 19 | 470 | 552 | -3.49% | 728 | 1 | City |
| St. Paul | 20 | 424 | 432 | -0.47% | 1,442 | 0 | City |
| Scotts Mills | 21 | 417 | 417 | 0% | 1,155 | 0 | City |
| Brooks | 22 | 289 | 621 | -2.36% | 567 | 1 | CDP |
| Marion | 23 | 289 | 416 | -0.69% | 252 | 1 | CDP |
| Detroit | 24 | 186 | 201 | -1.59% | 317 | 1 | City |
| Idanha | 25 | 157 | 155 | 0% | 212 | 1 | City |
Salem is the largest city in Marion County, with a population of 181,513.
Idanha is the smallest city in Marion County, with a population of 157.
There are 25 cities in Marion County, Oregon.