11 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hudson | 1 | 15,136 | 14,821 | 0.35% | 2,221 | 7 | City |
| New Richmond | 2 | 11,241 | 10,154 | 1.64% | 954 | 12 | City |
| Baldwin | 3 | 4,381 | 4,294 | 0.34% | 1,360 | 3 | Village |
| North Hudson | 4 | 3,821 | 3,814 | 0.03% | 2,440 | 2 | Village |
| Somerset | 5 | 3,557 | 3,031 | 2.54% | 1,072 | 3 | Village |
| Roberts | 6 | 2,749 | 1,930 | 5.25% | 911 | 3 | Village |
| Hammond | 7 | 1,865 | 1,913 | -0.43% | 863 | 2 | Village |
| Woodville | 8 | 1,403 | 1,397 | 0.07% | 781 | 2 | Village |
| Glenwood City | 9 | 1,247 | 1,306 | -0.8% | 359 | 3 | City |
| Deer Park | 10 | 241 | 250 | -0.41% | 266 | 1 | Village |
| Wilson | 11 | 200 | 208 | -0.5% | 117 | 2 | Village |
Hudson is the largest city in St. Croix County, with a population of 15,136.
Wilson is the smallest city in St. Croix County, with a population of 200.
There are 11 cities in St. Croix County, Wisconsin.