11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hudson | 1 | 15,083 | 14,821 | 0.35% | 2,214 | 7 | City |
| New Richmond | 2 | 11,060 | 10,154 | 1.66% | 939 | 12 | City |
| Baldwin | 3 | 4,366 | 4,294 | 0.32% | 1,355 | 3 | Village |
| North Hudson | 4 | 3,820 | 3,814 | 0.03% | 2,439 | 2 | Village |
| Somerset | 5 | 3,469 | 3,031 | 2.57% | 1,046 | 3 | Village |
| Roberts | 6 | 2,612 | 1,930 | 5.49% | 866 | 3 | Village |
| Hammond | 7 | 1,873 | 1,913 | -0.43% | 867 | 2 | Village |
| Woodville | 8 | 1,402 | 1,397 | 0.07% | 780 | 2 | Village |
| Glenwood City | 9 | 1,257 | 1,306 | -0.79% | 362 | 3 | City |
| Deer Park | 10 | 242 | 250 | -0.82% | 267 | 1 | Village |
| Wilson | 11 | 201 | 208 | -0.99% | 118 | 2 | Village |
Hudson is the largest city in St. Croix County, with a population of 15,083.
Wilson is the smallest city in St. Croix County, with a population of 201.
There are 11 cities in St. Croix County, Wisconsin.