19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Munising | 1 | 2,758 | 2,872 | -0.83% | 14 | 202 | Township |
| Munising | 2 | 2,758 | 2,874 | -0.83% | 14 | 202 | Township |
| Munising | 3 | 1,942 | 1,971 | -0.31% | 369 | 5 | City |
| Munising | 4 | 1,942 | 1,972 | -0.31% | 369 | 5 | City |
| Rock River | 5 | 1,229 | 1,240 | -0.32% | 15 | 81 | Township |
| Rock River | 6 | 1,229 | 1,242 | -0.32% | 15 | 81 | Township |
| Au Train | 7 | 1,012 | 1,022 | -0.3% | 7 | 141 | Township |
| Au Train | 8 | 1,012 | 1,023 | -0.3% | 7 | 141 | Township |
| Mathias | 9 | 525 | 531 | -0.38% | 7 | 71 | Township |
| Mathias | 10 | 525 | 531 | -0.38% | 7 | 71 | Township |
| Limestone | 11 | 385 | 389 | -0.52% | 5 | 74 | Township |
| Limestone | 12 | 385 | 389 | -0.52% | 5 | 74 | Township |
| Onota | 13 | 368 | 370 | -0.27% | 4 | 88 | Township |
| Onota | 14 | 368 | 370 | -0.27% | 4 | 88 | Township |
| Grand Marais | 15 | 320 | 317 | 7.02% | 169 | 2 | CDP |
| Chatham | 16 | 214 | 218 | -0.47% | 87 | 2 | Village |
| Chatham | 17 | 214 | 218 | -0.47% | 87 | 2 | Village |
| Grand Island | 18 | 31 | 31 | 0% | 1 | 22 | Township |
| Grand Island | 19 | 31 | 31 | 0% | 1 | 22 | Township |
Munising is the largest city in Alger County, with a population of 2,758.
Grand Island is the smallest city in Alger County, with a population of 31.
There are 19 cities in Alger County, Michigan.