63 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Le Ray town | 1 | 25,394 | 25,499 | -0.47% | 345 | 73.61 | Town |
| Watertown | 2 | 23,897 | 24,546 | -0.54% | 2,646 | 9.03 | City |
| Fort Drum | 3 | 17,134 | 13,034 | 1.66% | 1,195 | 14.34 | CDP |
| Brownville town | 4 | 5,736 | 5,828 | -0.45% | 97 | 58.92 | Town |
| Wilna town | 5 | 5,524 | 5,696 | -1% | 71 | 77.98 | Town |
| Watertown town | 6 | 5,421 | 5,833 | -0.44% | 152 | 35.69 | Town |
| Adams town | 7 | 4,848 | 4,946 | -0.64% | 115 | 42.23 | Town |
| Clayton town | 8 | 4,568 | 4,731 | -0.95% | 55 | 82.52 | Town |
| Champion town | 9 | 4,458 | 4,543 | -0.62% | 101 | 44.03 | Town |
| Alexandria town | 10 | 3,660 | 3,730 | -0.6% | 50 | 72.58 | Town |
| Calcium | 11 | 3,655 | 3,548 | 0.3% | 652 | 5.61 | CDP |
| Ellisburg town | 12 | 3,278 | 3,339 | -0.61% | 38 | 85.22 | Town |
| Carthage | 13 | 3,230 | 3,315 | -0.52% | 1,332 | 2.42 | Village |
| Pamelia town | 14 | 3,224 | 3,325 | -0.74% | 95 | 34.10 | Town |
| Hounsfield town | 15 | 3,207 | 3,260 | -0.56% | 66 | 48.95 | Town |
| Rutland town | 16 | 2,942 | 3,020 | -0.78% | 65 | 45.21 | Town |
| Orleans town | 17 | 2,732 | 2,782 | -0.58% | 38 | 71.25 | Town |
| Cape Vincent town | 18 | 2,730 | 2,678 | 3.88% | 49 | 56.28 | Town |
| Theresa town | 19 | 2,595 | 2,640 | -0.69% | 40 | 65.12 | Town |
| Lyme town | 20 | 2,203 | 2,285 | -0.99% | 39 | 55.87 | Town |
| Philadelphia town | 21 | 1,923 | 1,965 | -0.57% | 51 | 37.67 | Town |
| West Carthage | 22 | 1,745 | 1,767 | -0.23% | 1,334 | 1.31 | Village |
| Clayton | 23 | 1,679 | 1,733 | -0.65% | 1,048 | 1.60 | Village |
| Adams | 24 | 1,671 | 1,688 | -0.18% | 1,156 | 1.45 | Village |
| Antwerp town | 25 | 1,647 | 1,679 | -0.66% | 16 | 105.96 | Town |
| Henderson town | 26 | 1,413 | 1,435 | -0.49% | 34 | 41.18 | Town |
| Sackets Harbor | 27 | 1,358 | 1,372 | -0.22% | 589 | 2.31 | Village |
| Great Bend | 28 | 1,299 | 1,329 | 2.36% | 224 | 5.79 | CDP |
| Black River | 29 | 1,221 | 1,260 | -0.65% | 686 | 1.78 | Village |
| Rodman town | 30 | 1,166 | 1,193 | -0.77% | 28 | 42.29 | Town |
| Philadelphia | 31 | 1,135 | 1,172 | -0.61% | 1,185 | 0.96 | Village |
| Dexter | 32 | 1,006 | 1,011 | -0.1% | 1,511 | 0.67 | Village |
| Alexandria Bay | 33 | 945 | 959 | -0.32% | 1,262 | 0.75 | Village |
| Brownville | 34 | 935 | 945 | -0.21% | 1,498 | 0.62 | Village |
| Pamelia Center | 35 | 896 | 441 | 4.92% | 640 | 1.40 | CDP |
| Lorraine town | 36 | 892 | 916 | -0.78% | 23 | 39 | Town |
| Adams Center | 37 | 886 | 1,000 | -4.83% | 182 | 4.86 | CDP |
| Theresa | 38 | 738 | 760 | -0.54% | 584 | 1.26 | Village |
| Cape Vincent | 39 | 724 | 734 | -0.28% | 1,030 | 0.70 | Village |
| Evans Mills | 40 | 618 | 625 | -0.16% | 756 | 0.82 | Village |
| Chaumont | 41 | 591 | 608 | -0.51% | 601 | 0.98 | Village |
| La Fargeville | 42 | 510 | 733 | -1.35% | 154 | 3.31 | CDP |
| Antwerp | 43 | 509 | 516 | -0.2% | 507 | 1 | Village |
| Felts Mills | 44 | 444 | 451 | 0.91% | 758 | 0.59 | CDP |
| Glen Park | 45 | 444 | 446 | 0% | 622 | 0.71 | Village |
| Pierrepont Manor | 46 | 404 | 416 | 3.06% | 522 | 0.77 | CDP |
| Depauville | 47 | 341 | 224 | -4.21% | 35 | 9.82 | CDP |
| Mannsville | 48 | 318 | 322 | -0.31% | 355 | 0.90 | Village |
| Belleville | 49 | 305 | 279 | 1.67% | 464 | 0.66 | CDP |
| Plessis | 50 | 292 | 370 | 3.18% | 844 | 0.35 | CDP |
| Thousand Island Park | 51 | 270 | 155 | 7.14% | 909 | 0.30 | CDP |
| Deferiet | 52 | 253 | 258 | -0.39% | 375 | 0.68 | Village |
| Henderson | 53 | 241 | 236 | 0.42% | 459 | 0.53 | CDP |
| Redwood | 54 | 229 | 483 | -9.84% | 116 | 1.97 | CDP |
| Ellisburg | 55 | 213 | 215 | 0% | 213 | 1 | Village |
| Rodman | 56 | 203 | 142 | 1.5% | 1,277 | 0.16 | CDP |
| Worth town | 57 | 197 | 200 | -0.51% | 5 | 43.25 | Town |
| Natural Bridge | 58 | 132 | 228 | -10.81% | 103 | 1.28 | CDP |
| Oxbow | 59 | 120 | 122 | 0% | 297 | 0.40 | CDP |
| Lorraine | 60 | 99 | 55 | -4.81% | 202 | 0.49 | CDP |
| Fishers Landing | 61 | 68 | 76 | 7.94% | 151 | 0.45 | CDP |
| Herrings | 62 | 41 | 132 | 7.89% | 266 | 0.15 | CDP |
| Three Mile Bay | 63 | 22 | 182 | -38.89% | 78 | 0.28 | CDP |
Le Ray town is the largest city in Jefferson County, with a population of 25,394.
Three Mile Bay is the smallest city in Jefferson County.
There are 63 cities in Jefferson County, New York.