19 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Salem | 1 | 182,620 | 175,977 | 0.61% | 3,732 | 49 | City |
| Keizer | 2 | 39,065 | 39,325 | -0.11% | 5,437 | 7 | City |
| Woodburn | 3 | 32,639 | 26,068 | 3.47% | 5,279 | 6 | City |
| Silverton | 4 | 10,343 | 10,487 | -0.23% | 2,949 | 4 | City |
| Stayton | 5 | 8,662 | 8,238 | 0.83% | 2,774 | 3 | City |
| Aumsville | 6 | 4,198 | 4,252 | -0.21% | 3,718 | 1 | City |
| Mount Angel | 7 | 3,464 | 3,379 | 0.41% | 3,049 | 1 | City |
| Hubbard | 8 | 3,386 | 3,433 | -0.24% | 4,222 | 1 | City |
| Jefferson | 9 | 3,279 | 3,329 | -0.24% | 3,826 | 1 | City |
| Sublimity | 10 | 2,835 | 2,967 | -0.77% | 3,022 | 1 | City |
| Gervais | 11 | 2,557 | 2,598 | -0.27% | 6,283 | 0 | City |
| Turner | 12 | 2,396 | 2,450 | -0.37% | 1,672 | 1 | City |
| Aurora | 13 | 1,112 | 1,142 | -0.45% | 2,298 | 0 | City |
| Donald | 14 | 1,015 | 1,009 | 0.1% | 2,678 | 0 | City |
| Gates | 15 | 454 | 552 | -3.4% | 703 | 1 | City |
| St. Paul | 16 | 423 | 432 | -0.24% | 1,439 | 0 | City |
| Scotts Mills | 17 | 417 | 417 | 0% | 1,155 | 0 | City |
| Detroit | 18 | 183 | 201 | -1.61% | 312 | 1 | City |
| Idanha | 19 | 158 | 155 | 0.64% | 214 | 1 | City |
Salem is the largest city in Marion County, with a population of 182,620.
Idanha is the smallest city in Marion County, with a population of 158.
There are 19 cities in Marion County, Oregon.