12 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Decatur | 1 | 67,655 | 70,978 | -0.81% | 1,532 | 44 | City |
| Mount Zion | 2 | 5,838 | 6,015 | -0.49% | 1,368 | 4 | Village |
| Forsyth | 3 | 3,618 | 3,732 | -0.52% | 1,169 | 3 | Village |
| Maroa | 4 | 1,511 | 1,576 | -0.72% | 857 | 2 | City |
| Harristown | 5 | 1,249 | 1,312 | -0.79% | 695 | 2 | Village |
| Long Creek | 6 | 1,217 | 1,261 | -0.57% | 431 | 3 | Village |
| Macon | 7 | 1,115 | 1,169 | -0.8% | 880 | 1 | City |
| Warrensburg | 8 | 1,073 | 1,112 | -0.56% | 1,474 | 1 | Village |
| Blue Mound | 9 | 1,070 | 1,130 | -0.93% | 1,829 | 1 | Village |
| Argenta | 10 | 864 | 911 | -0.92% | 1,323 | 1 | Village |
| Oreana | 11 | 843 | 888 | -0.82% | 1,801 | 0 | Village |
| Niantic | 12 | 577 | 609 | -0.86% | 555 | 1 | Village |
Decatur is the largest city in Macon County, with a population of 67,655.
Niantic is the smallest city in Macon County, with a population of 577.
There are 12 cities in Macon County, Illinois.