13 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lewistown | 1 | 8,351 | 8,564 | -0.51% | 4,114 | 2 | Borough |
| Granville | 2 | 4,573 | 4,627 | -0.09% | 114 | 40 | Township |
| Brown | 3 | 4,193 | 4,123 | 0.55% | 128 | 33 | Township |
| Union | 4 | 3,681 | 3,658 | 0.05% | 145 | 25 | Township |
| Decatur | 5 | 2,915 | 2,966 | -0.38% | 65 | 45 | Township |
| Menno | 6 | 2,025 | 1,975 | 0.9% | 85 | 24 | Township |
| Burnham | 7 | 1,959 | 1,991 | -0.36% | 1,862 | 1 | Borough |
| Bratton | 8 | 1,177 | 1,190 | 0.09% | 36 | 33 | Township |
| Granville | 9 | 893 | 895 | -0.11% | 36 | 25 | Township |
| McClure | 10 | 881 | 891 | -0.23% | 235 | 4 | Borough |
| Juniata Terrace | 11 | 550 | 564 | -0.54% | 3,274 | 0 | Borough |
| McVeytown | 12 | 333 | 342 | -0.6% | 3,505 | 0 | Borough |
| Newton Hamilton | 13 | 198 | 196 | 0% | 1,277 | 0 | Borough |
Lewistown is the largest city in Mifflin County, with a population of 8,351.
Newton Hamilton is the smallest city in Mifflin County, with a population of 198.
There are 13 cities in Mifflin County, Pennsylvania.