8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| John Day | 1 | 1,623 | 1,676 | -0.55% | 718 | 2 | City |
| Prairie City | 2 | 807 | 836 | -0.62% | 814 | 1 | City |
| Canyon City | 3 | 634 | 660 | -0.63% | 450 | 1 | Town |
| Mount Vernon | 4 | 546 | 549 | 0% | 799 | 1 | City |
| Long Creek | 5 | 166 | 171 | -0.6% | 162 | 1 | City |
| Seneca | 6 | 160 | 166 | -0.62% | 201 | 1 | City |
| Dayville | 7 | 129 | 132 | 0% | 245 | 1 | Town |
| Monument | 8 | 111 | 111 | 0% | 218 | 1 | City |
John Day is the largest city in Grant County, with a population of 1,623.
Monument is the smallest city in Grant County, with a population of 111.
There are 8 cities in Grant County, Oregon.