| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 182,902 | 175,985 | 0.62% | 3,738 | 49 | City |
| Keizer | 2 | 39,115 | 39,328 | -0.06% | 5,444 | 7 | City |
| Woodburn | 3 | 33,046 | 26,058 | 3.44% | 5,345 | 6 | City |
| Silverton | 4 | 10,429 | 10,472 | -0.2% | 2,974 | 4 | City |
| Stayton | 5 | 8,560 | 8,235 | 0.85% | 2,741 | 3 | City |
| Aumsville | 6 | 4,237 | 4,254 | -0.09% | 3,753 | 1 | City |
| Mount Angel | 7 | 3,470 | 3,385 | 0.46% | 3,055 | 1 | City |
| Hubbard | 8 | 3,390 | 3,439 | -0.26% | 4,227 | 1 | City |
| Jefferson | 9 | 3,289 | 3,341 | -0.3% | 3,838 | 1 | City |
| Sublimity | 10 | 2,861 | 2,967 | -0.73% | 3,050 | 1 | City |
| Gervais | 11 | 2,566 | 2,598 | -0.23% | 6,305 | 0 | City |
| Turner | 12 | 2,404 | 2,450 | -0.33% | 1,678 | 1 | City |
| Aurora | 13 | 1,108 | 1,141 | -0.45% | 2,289 | 0 | City |
| Donald | 14 | 1,008 | 1,004 | 0% | 2,660 | 0 | City |
| Gates | 15 | 463 | 553 | -3.94% | 717 | 1 | City |
| St. Paul | 16 | 427 | 433 | -0.47% | 1,452 | 0 | City |
| Scotts Mills | 17 | 413 | 417 | -0.24% | 1,144 | 0 | City |
| Detroit | 18 | 187 | 202 | -1.58% | 319 | 1 | City |
| Idanha | 19 | 159 | 157 | 0% | 215 | 1 | City |
Salem is the largest city in Marion County, with a population of 182,902.
Idanha is the smallest city in Marion County, with a population of 159.
There are 19 cities in Marion County, Oregon.