10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Boardman | 1 | 4,469 | 3,833 | 2.85% | 1,109 | 4 | City |
| Boardman | 2 | 4,469 | 3,846 | 2.85% | 1,109 | 4 | City |
| Irrigon | 3 | 2,014 | 2,008 | 0% | 1,553 | 1 | City |
| Irrigon | 4 | 2,014 | 2,013 | 0% | 1,553 | 1 | City |
| Heppner | 5 | 1,100 | 1,189 | -1.7% | 894 | 1 | City |
| Heppner | 6 | 1,100 | 1,192 | -1.7% | 894 | 1 | City |
| Ione | 7 | 324 | 343 | -1.22% | 427 | 1 | City |
| Ione | 8 | 324 | 343 | -1.22% | 427 | 1 | City |
| Lexington | 9 | 222 | 240 | -1.77% | 508 | 0 | Town |
| Lexington | 10 | 222 | 240 | -1.77% | 508 | 0 | Town |
Boardman is the largest city in Morrow County, with a population of 4,469.
Lexington is the smallest city in Morrow County, with a population of 222.
There are 10 cities in Morrow County, Oregon.