8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rock Rapids | 1 | 2,757 | 2,612 | 0.88% | 654 | 4 | City |
| George | 2 | 1,120 | 1,078 | 0.63% | 488 | 2 | City |
| Inwood | 3 | 980 | 926 | 0.93% | 692 | 1 | City |
| Larchwood | 4 | 968 | 926 | 0.73% | 933 | 1 | City |
| Doon | 5 | 653 | 614 | 1.08% | 834 | 1 | City |
| Little Rock | 6 | 450 | 441 | 0.45% | 443 | 1 | City |
| Lester | 7 | 315 | 296 | 0.96% | 173 | 2 | City |
| Alvord | 8 | 220 | 207 | 0.92% | 381 | 1 | City |
Rock Rapids is the largest city in Lyon County, with a population of 2,757.
Alvord is the smallest city in Lyon County, with a population of 220.
There are 8 cities in Lyon County, Iowa.