12 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hudson | 1 | 15,939 | 14,773 | 1.48% | 2,339 | 6.81 | City |
| New Richmond | 2 | 11,062 | 10,169 | 1.64% | 1,011 | 10.95 | City |
| Baldwin | 3 | 4,415 | 4,292 | 0.57% | 1,371 | 3.22 | Village |
| North Hudson | 4 | 3,940 | 3,810 | 0.66% | 2,516 | 1.57 | Village |
| Somerset | 5 | 3,343 | 3,035 | 1.89% | 1,008 | 3.32 | Village |
| Roberts | 6 | 2,181 | 1,958 | 2.11% | 845 | 2.58 | Village |
| Hammond | 7 | 1,836 | 1,873 | -0.38% | 850 | 2.16 | Village |
| Woodville | 8 | 1,423 | 1,388 | 0.49% | 792 | 1.80 | Village |
| Glenwood City | 9 | 1,301 | 1,308 | -0.08% | 375 | 3.47 | City |
| Deer Park | 10 | 242 | 252 | -0.82% | 267 | 0.91 | Village |
| Wilson | 11 | 202 | 209 | -0.49% | 118 | 1.71 | Village |
| Houlton | 12 | 40 | 105 | -36.51% | 27 | 1.46 | CDP |
Hudson is the largest city in St. Croix County, with a population of 15,939.
Houlton is the smallest city in St. Croix County.
There are 12 cities in St. Croix County, Wisconsin.