| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Carmel | 1 | 34,723 | 33,616 | 0.82% | 968 | 36 | Town |
| Southeast | 2 | 18,353 | 18,026 | -0.14% | 579 | 32 | Town |
| Putnam Valley | 3 | 11,737 | 11,733 | -0.21% | 286 | 41 | Town |
| Patterson | 4 | 11,630 | 11,543 | -0.09% | 361 | 32 | Town |
| Philipstown | 5 | 9,896 | 9,824 | -0.14% | 203 | 49 | Town |
| Brewster | 6 | 2,511 | 2,506 | 0.08% | 5,114 | 0 | Village |
| Cold Spring | 7 | 2,002 | 1,984 | 0.2% | 3,370 | 1 | Village |
| Nelsonville | 8 | 637 | 625 | 0.31% | 616 | 1 | Village |
Carmel is the largest city in Putnam County, with a population of 34,723.
Nelsonville is the smallest city in Putnam County, with a population of 637.
There are 8 cities in Putnam County, New York.