| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairbury | 1 | 3,785 | 3,973 | -0.71% | 1,493 | 3 | City |
| Plymouth | 2 | 359 | 363 | 0% | 1,136 | 0 | Village |
| Diller | 3 | 271 | 249 | 1.5% | 642 | 0 | Village |
| Daykin | 4 | 152 | 156 | -0.65% | 927 | 0 | Village |
| Endicott | 5 | 110 | 112 | 0% | 240 | 0 | Village |
| Jansen | 6 | 101 | 102 | 0% | 323 | 0 | Village |
| Harbine | 7 | 51 | 53 | -1.92% | 486 | 0 | Village |
| Steele City | 8 | 50 | 52 | -1.96% | 215 | 0 | Village |
Fairbury is the largest city in Jefferson County, with a population of 3,785.
Steele City is the smallest city in Jefferson County, with a population of 50.
There are 8 cities in Jefferson County, Nebraska.