| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Marshall | 1 | 24,720 | 23,330 | 1.03% | 831 | 30 | City |
| Hallsville | 2 | 5,035 | 4,290 | 2.86% | 1,261 | 4 | City |
| Waskom | 3 | 1,993 | 1,906 | 0.66% | 744 | 3 | City |
| Scottsville | 4 | 342 | 332 | 0.29% | 260 | 1 | City |
| Uncertain | 5 | 90 | 89 | 0% | 168 | 1 | City |
Marshall is the largest city in Harrison County, with a population of 24,720.
Uncertain is the smallest city in Harrison County, with a population of 90.
There are 5 cities in Harrison County, Texas.