| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Manchester | 1 | 5,407 | 5,075 | 0.93% | 1,117 | 5 | City |
| Earlville | 2 | 706 | 711 | -0.14% | 1,281 | 1 | City |
| Hopkinton | 3 | 618 | 620 | 0% | 963 | 1 | City |
| Delhi | 4 | 452 | 416 | 1.12% | 477 | 1 | City |
| Colesburg | 5 | 379 | 385 | -0.26% | 1,289 | 0 | City |
| Ryan | 6 | 345 | 346 | -0.29% | 788 | 0 | City |
| Greeley | 7 | 209 | 213 | -0.48% | 557 | 0 | City |
| Dundee | 8 | 189 | 193 | -0.53% | 600 | 0 | City |
| Delaware | 9 | 138 | 140 | -0.72% | 189 | 1 | City |
| Masonville | 10 | 97 | 99 | -1.02% | 297 | 0 | City |
Manchester is the largest city in Delaware County, with a population of 5,407.
Masonville is the smallest city in Delaware County, with a population of 97.
There are 10 cities in Delaware County, Iowa.