10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Manchester | 1 | 5,349 | 5,074 | 1.04% | 1,105 | 4.84 | City |
| Earlville | 2 | 717 | 717 | 0% | 1,301 | 0.55 | City |
| Hopkinton | 3 | 625 | 622 | 0.16% | 974 | 0.64 | City |
| Delhi | 4 | 444 | 414 | 1.37% | 468 | 0.95 | City |
| Colesburg | 5 | 381 | 386 | -0.26% | 1,296 | 0.29 | City |
| Ryan | 6 | 345 | 347 | 0% | 788 | 0.44 | City |
| Greeley | 7 | 216 | 216 | 0% | 576 | 0.38 | City |
| Dundee | 8 | 194 | 194 | 0% | 616 | 0.32 | City |
| Delaware | 9 | 138 | 140 | 0% | 189 | 0.73 | City |
| Masonville | 10 | 99 | 99 | 0% | 303 | 0.33 | City |
Manchester is the largest city in Delaware County, with a population of 5,349.
Masonville is the smallest city in Delaware County.
There are 10 cities in Delaware County, Iowa.