48 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| East Greenbush | 1 | 16,674 | 16,837 | 0.2% | 694 | 24 | Town |
| East Greenbush | 2 | 16,674 | 16,807 | 0.2% | 694 | 24 | Town |
| North Greenbush | 3 | 13,617 | 13,298 | 1.19% | 735 | 19 | Town |
| North Greenbush | 4 | 13,617 | 13,298 | 1.19% | 735 | 19 | Town |
| Schodack | 5 | 13,011 | 12,968 | 0.42% | 210 | 62 | Town |
| Schodack | 6 | 13,011 | 12,948 | 0.42% | 210 | 62 | Town |
| Brunswick | 7 | 12,561 | 12,588 | 0.34% | 283 | 44 | Town |
| Brunswick | 8 | 12,561 | 12,585 | 0.34% | 283 | 44 | Town |
| Rensselaer | 9 | 9,515 | 9,213 | 0.66% | 2,993 | 3 | City |
| Rensselaer | 10 | 9,515 | 9,205 | 0.66% | 2,993 | 3 | City |
| Sand Lake | 11 | 8,389 | 8,341 | 0.43% | 239 | 35 | Town |
| Sand Lake | 12 | 8,389 | 8,336 | 0.43% | 239 | 35 | Town |
| Schaghticoke | 13 | 7,360 | 7,437 | 0.27% | 148 | 50 | Town |
| Schaghticoke | 14 | 7,360 | 7,396 | 0.27% | 148 | 50 | Town |
| East Greenbush | 15 | 7,092 | 6,299 | 2.52% | 1,811 | 4 | CDP |
| Hoosick | 16 | 6,748 | 6,716 | 0.78% | 107 | 63 | Town |
| Hoosick | 17 | 6,748 | 6,702 | 0.78% | 107 | 63 | Town |
| Hampton Manor | 18 | 6,076 | 5,161 | 4.18% | 2,027 | 3 | CDP |
| Pittstown | 19 | 5,462 | 5,538 | 0.2% | 89 | 62 | Town |
| Pittstown | 20 | 5,462 | 5,527 | 0.2% | 89 | 62 | Town |
| Nassau | 21 | 4,523 | 4,549 | 0.29% | 102 | 44 | Town |
| Nassau | 22 | 4,523 | 4,543 | 0.29% | 102 | 44 | Town |
| Poestenkill | 23 | 4,398 | 4,317 | 1.03% | 136 | 32 | Town |
| Poestenkill | 24 | 4,398 | 4,313 | 1.03% | 136 | 32 | Town |
| Wynantskill | 25 | 3,785 | 3,420 | 0.91% | 1,107 | 3 | CDP |
| West Sand Lake | 26 | 3,465 | 3,391 | 1.58% | 727 | 5 | CDP |
| Hoosick Falls | 27 | 3,187 | 3,214 | -0.09% | 1,994 | 2 | Village |
| Hoosick Falls | 28 | 3,187 | 3,202 | -0.09% | 1,994 | 2 | Village |
| Stephentown | 29 | 2,798 | 2,790 | 0.54% | 48 | 58 | Town |
| Stephentown | 30 | 2,798 | 2,788 | 0.54% | 48 | 58 | Town |
| Grafton | 31 | 2,112 | 2,054 | 0.76% | 47 | 45 | Town |
| Grafton | 32 | 2,112 | 2,053 | 0.76% | 47 | 45 | Town |
| Berlin | 33 | 1,712 | 1,703 | 0.71% | 29 | 60 | Town |
| Berlin | 34 | 1,712 | 1,702 | 0.71% | 29 | 60 | Town |
| Averill Park | 35 | 1,587 | 1,466 | -0.44% | 393 | 4 | CDP |
| Castleton-on-Hudson | 36 | 1,470 | 1,480 | -0.07% | 2,059 | 1 | Village |
| Castleton-on-Hudson | 37 | 1,470 | 1,472 | -0.07% | 2,059 | 1 | Village |
| Petersburgh | 38 | 1,383 | 1,376 | 0.44% | 33 | 42 | Town |
| Petersburgh | 39 | 1,383 | 1,374 | 0.44% | 33 | 42 | Town |
| Nassau | 40 | 1,087 | 1,106 | -0.37% | 1,555 | 1 | Village |
| Nassau | 41 | 1,087 | 1,105 | -0.37% | 1,555 | 1 | Village |
| Poestenkill | 42 | 677 | 814 | -3.7% | 115 | 6 | CDP |
| Schaghticoke | 43 | 549 | 560 | -0.36% | 724 | 1 | Village |
| Schaghticoke | 44 | 549 | 559 | -0.36% | 724 | 1 | Village |
| East Nassau | 45 | 514 | 522 | -0.39% | 106 | 5 | Village |
| East Nassau | 46 | 514 | 521 | -0.39% | 106 | 5 | Village |
| Valley Falls | 47 | 451 | 459 | -0.44% | 974 | 0 | Village |
| Valley Falls | 48 | 451 | 458 | -0.44% | 974 | 0 | Village |
East Greenbush is the largest city in Rensselaer County, with a population of 16,674.
Valley Falls is the smallest city in Rensselaer County, with a population of 451.
There are 48 cities in Rensselaer County, New York.