13 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lewistown | 1 | 8,309 | 8,564 | -0.5% | 4,093 | 2 | Borough |
| Granville | 2 | 4,569 | 4,627 | -0.09% | 114 | 40 | Township |
| Brown | 3 | 4,216 | 4,123 | 0.55% | 128 | 33 | Township |
| Union | 4 | 3,683 | 3,658 | 0.05% | 145 | 25 | Township |
| Decatur | 5 | 2,904 | 2,966 | -0.38% | 64 | 45 | Township |
| Menno | 6 | 2,043 | 1,975 | 0.89% | 86 | 24 | Township |
| Burnham | 7 | 1,953 | 1,991 | -0.31% | 1,856 | 1 | Borough |
| Bratton | 8 | 1,178 | 1,190 | 0.08% | 36 | 33 | Township |
| Granville | 9 | 892 | 895 | -0.11% | 36 | 25 | Township |
| McClure | 10 | 879 | 891 | -0.23% | 234 | 4 | Borough |
| Juniata Terrace | 11 | 547 | 564 | -0.55% | 3,256 | 0 | Borough |
| McVeytown | 12 | 331 | 342 | -0.6% | 3,484 | 0 | Borough |
| Newton Hamilton | 13 | 199 | 196 | 0.51% | 1,284 | 0 | Borough |
Lewistown is the largest city in Mifflin County, with a population of 8,309.
Newton Hamilton is the smallest city in Mifflin County, with a population of 199.
There are 13 cities in Mifflin County, Pennsylvania.