| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Metropolis | 1 | 5,683 | 5,943 | -0.77% | 944 | 6 | City |
| Brookport | 2 | 684 | 723 | -1.01% | 1,047 | 1 | City |
| Joppa | 3 | 326 | 348 | -1.21% | 671 | 0 | Village |
| New Grand Chain | 4 | 140 | 154 | -2.1% | 134 | 1 | Village |
Metropolis is the largest city in Massac County, with a population of 5,683.
New Grand Chain is the smallest city in Massac County, with a population of 140.
There are 4 cities in Massac County, Illinois.