| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rock Rapids | 1 | 2,758 | 2,613 | 0.91% | 655 | 4 | City |
| George | 2 | 1,099 | 1,080 | 0.55% | 479 | 2 | City |
| Inwood | 3 | 975 | 926 | 1.04% | 688 | 1 | City |
| Larchwood | 4 | 960 | 925 | 0.73% | 926 | 1 | City |
| Doon | 5 | 646 | 610 | 0.94% | 825 | 1 | City |
| Little Rock | 6 | 441 | 440 | 0.46% | 434 | 1 | City |
| Lester | 7 | 309 | 297 | 0.98% | 169 | 2 | City |
| Alvord | 8 | 219 | 209 | 0.92% | 380 | 1 | City |
Rock Rapids is the largest city in Lyon County, with a population of 2,758.
Alvord is the smallest city in Lyon County, with a population of 219.
There are 8 cities in Lyon County, Iowa.