Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Pop. | 2020 Pop. | Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Hamilton township | 1 | 91,845 | 92,057 | 0.22% | 2,328 | 39.4 | Township |
| Trenton | 2 | 89,705 | 90,592 | 0.1% | 11,794 | 7.6 | City |
| Ewing township | 3 | 34,845 | 37,239 | 0.27% | 2,291 | 15.2 | Township |
| Lawrence township | 4 | 31,781 | 33,047 | 0.03% | 1,463 | 21.7 | Township |
| West Windsor township | 5 | 30,979 | 29,529 | 1.54% | 1,213 | 25.5 | Township |
| Princeton | 6 | 30,272 | 30,610 | -0.06% | 1,687 | 17.9 | Township |
| East Windsor township | 7 | 29,753 | 29,937 | -0.02% | 1,911 | 15.6 | Township |
| Hopewell township | 8 | 17,374 | 17,442 | -0.05% | 299 | 58.1 | Township |
| Robbinsville township | 9 | 15,396 | 15,435 | 0.23% | 753 | 20.4 | Township |
| Hightstown borough | 10 | 5,854 | 5,883 | 0.02% | 4,748 | 1.2 | Borough |
| Hopewell township | 11 | 4,358 | 4,377 | 0.11% | 146 | 29.9 | Township |
| Pennington borough | 12 | 2,865 | 2,796 | 0.88% | 2,981 | 1.0 | Borough |
| Hopewell borough | 13 | 1,894 | 1,899 | 0% | 2,616 | 0.7 | Borough |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Hamilton township is the largest city in Mercer County.
Hopewell borough is the smallest city in Mercer County.
There are 13 cities in Mercer County, New Jersey.