13 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Lincoln | 1 | 4,760 | 4,524 | 1.06% | 112 | 42 | Township |
| Lake | 2 | 2,459 | 2,366 | 0.78% | 62 | 40 | Township |
| Jefferson | 3 | 2,025 | 2,002 | 0.35% | 45 | 45 | Township |
| Kentland | 4 | 1,624 | 1,633 | -0.12% | 1,203 | 1 | Town |
| Beaver | 5 | 1,539 | 1,512 | 0.46% | 38 | 41 | Township |
| Iroquois | 6 | 1,256 | 1,236 | 0.48% | 34 | 37 | Township |
| Grant | 7 | 1,101 | 1,097 | 0.36% | 31 | 36 | Township |
| Morocco | 8 | 1,082 | 1,075 | 0.09% | 1,015 | 1 | Town |
| Goodland | 9 | 970 | 975 | -0.1% | 1,275 | 1 | Town |
| Brook | 10 | 943 | 937 | 0.11% | 1,393 | 1 | Town |
| Jackson | 11 | 391 | 384 | 0% | 11 | 37 | Township |
| McClellan | 12 | 224 | 216 | 0.45% | 5 | 42 | Township |
| Mount Ayr | 13 | 116 | 116 | 0% | 663 | 0 | Town |
Lincoln is the largest city in Newton County, with a population of 4,760.
Mount Ayr is the smallest city in Newton County, with a population of 116.
There are 13 cities in Newton County, Indiana.