25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 178,425 | 175,942 | 0.28% | 3,646 | 48.93 | City |
| Keizer | 2 | 38,048 | 39,338 | -0.67% | 5,295 | 7.18 | City |
| Woodburn | 3 | 31,069 | 25,979 | 3.39% | 5,303 | 5.86 | City |
| Hayesville | 4 | 22,294 | 22,189 | 0.71% | 7,456 | 2.99 | CDP |
| Four Corners | 5 | 16,217 | 16,491 | 0.11% | 6,635 | 2.44 | CDP |
| Silverton | 6 | 10,248 | 10,480 | -0.45% | 2,922 | 3.51 | City |
| Stayton | 7 | 8,219 | 8,234 | -0.04% | 2,632 | 3.12 | City |
| Aumsville | 8 | 4,108 | 4,247 | -0.68% | 3,639 | 1.13 | City |
| Mount Angel | 9 | 3,447 | 3,401 | 0.26% | 3,034 | 1.14 | City |
| Hubbard | 10 | 3,330 | 3,435 | -0.63% | 4,152 | 0.80 | City |
| Jefferson | 11 | 3,221 | 3,335 | -0.71% | 3,758 | 0.86 | City |
| Sublimity | 12 | 2,874 | 2,968 | -0.66% | 3,064 | 0.94 | City |
| Gervais | 13 | 2,514 | 2,596 | -0.63% | 6,177 | 0.41 | City |
| Turner | 14 | 2,355 | 2,450 | -0.8% | 1,643 | 1.43 | City |
| Aurora | 15 | 1,102 | 1,142 | -0.72% | 2,277 | 0.48 | City |
| Donald | 16 | 992 | 1,011 | -0.4% | 2,617 | 0.38 | City |
| Mehama | 17 | 594 | 396 | 3.48% | 1,297 | 0.46 | CDP |
| Labish Village | 18 | 517 | 491 | 1.37% | 9,574 | 0.05 | CDP |
| Gates | 19 | 418 | 552 | -6.07% | 647 | 0.65 | City |
| St. Paul | 20 | 418 | 433 | -0.71% | 1,422 | 0.29 | City |
| Scotts Mills | 21 | 412 | 417 | -0.24% | 1,141 | 0.36 | City |
| Brooks | 22 | 289 | 621 | -2.36% | 567 | 0.51 | CDP |
| Marion | 23 | 289 | 416 | -0.69% | 252 | 1.15 | CDP |
| Detroit | 24 | 179 | 201 | -2.19% | 305 | 0.59 | City |
| Idanha | 25 | 156 | 156 | 0% | 211 | 0.74 | City |
Salem is the largest city in Marion County, with a population of 178,425.
Idanha is the smallest city in Marion County.
There are 25 cities in Marion County, Oregon.