| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Grundy Center | 1 | 2,816 | 2,806 | 0.07% | 1,096 | 3 | City |
| Reinbeck | 2 | 1,667 | 1,670 | -0.06% | 768 | 2 | City |
| Dike | 3 | 1,297 | 1,302 | -0.15% | 934 | 1 | City |
| Conrad | 4 | 1,085 | 1,091 | -0.09% | 883 | 1 | City |
| Wellsburg | 5 | 708 | 719 | -0.42% | 645 | 1 | City |
| Holland | 6 | 259 | 264 | -0.38% | 1,028 | 0 | City |
| Stout | 7 | 191 | 190 | 0% | 654 | 0 | City |
| Beaman | 8 | 154 | 158 | -0.65% | 824 | 0 | City |
| Morrison | 9 | 100 | 98 | 0% | 1,053 | 0 | City |
Grundy Center is the largest city in Grundy County, with a population of 2,816.
Morrison is the smallest city in Grundy County, with a population of 100.
There are 9 cities in Grundy County, Iowa.