22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Carrington | 1 | 2,003 | 2,080 | -0.79% | 845 | 2 | City |
| Carrington | 2 | 220 | 222 | -0.45% | 7 | 34 | Township |
| Glenfield | 3 | 95 | 95 | 0% | 693 | 0 | City |
| Birtsell | 4 | 90 | 91 | -1.1% | 3 | 36 | Township |
| Rose Hill | 5 | 79 | 79 | 0% | 2 | 35 | Township |
| Wyard | 6 | 76 | 76 | 0% | 2 | 35 | Township |
| Nordmore | 7 | 75 | 75 | 0% | 2 | 36 | Township |
| McHenry | 8 | 63 | 63 | 0% | 256 | 0 | City |
| Estabrook | 9 | 63 | 64 | -1.56% | 2 | 36 | Township |
| Larrabee | 10 | 59 | 58 | 0% | 2 | 35 | Township |
| Bordulac | 11 | 58 | 58 | 0% | 2 | 34 | Township |
| Grace City | 12 | 54 | 54 | 0% | 220 | 0 | City |
| Melville | 13 | 54 | 51 | 3.85% | 2 | 34 | Township |
| Glenfield | 14 | 50 | 50 | 0% | 1 | 36 | Township |
| Florance | 15 | 47 | 47 | 0% | 1 | 35 | Township |
| Longview | 16 | 45 | 48 | -2.17% | 1 | 35 | Township |
| Haven | 17 | 36 | 36 | 0% | 1 | 35 | Township |
| Rolling Prairie | 18 | 34 | 35 | 0% | 1 | 36 | Township |
| Bucephalia | 19 | 33 | 34 | 0% | 1 | 35 | Township |
| McHenry | 20 | 33 | 33 | 0% | 1 | 34 | Township |
| McKinnon | 21 | 23 | 24 | 0% | 1 | 36 | Township |
| Eastman | 22 | 15 | 15 | 0% | 0.00 | 36 | Township |
Carrington is the largest city in Foster County, with a population of 2,003.
Eastman is the smallest city in Foster County, with a population of 15.
There are 22 cities in Foster County, North Dakota.