| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hudson | 1 | 15,056 | 14,822 | 0.25% | 2,210 | 7 | City |
| New Richmond | 2 | 11,158 | 10,158 | 1.55% | 947 | 12 | City |
| Baldwin | 3 | 4,356 | 4,294 | 0.21% | 1,352 | 3 | Village |
| North Hudson | 4 | 3,800 | 3,816 | -0.08% | 2,427 | 2 | Village |
| Somerset | 5 | 3,492 | 3,028 | 2.46% | 1,052 | 3 | Village |
| Roberts | 6 | 2,625 | 1,929 | 5.29% | 870 | 3 | Village |
| Hammond | 7 | 1,847 | 1,903 | -0.54% | 855 | 2 | Village |
| Woodville | 8 | 1,389 | 1,394 | 0% | 773 | 2 | Village |
| Glenwood City | 9 | 1,243 | 1,300 | -0.88% | 358 | 3 | City |
| Deer Park | 10 | 241 | 251 | -0.82% | 266 | 1 | Village |
| Wilson | 11 | 200 | 208 | -0.99% | 117 | 2 | Village |
Hudson is the largest city in St. Croix County, with a population of 15,056.
Wilson is the smallest city in St. Croix County, with a population of 200.
There are 11 cities in St. Croix County, Wisconsin.