Hightstown is a borough in Mercer County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,494, reflecting an increase of 278 (+5.3%) from the 5,216 counted in the 2000 Census, which had in turn increased by 90 (+1.8%) from the 5,126 counted in the 1990 Census.
Hightstown was incorporated as a borough by an act of the New Jersey Legislature on March 5, 1853, within portions of East Windsor Township. The borough became fully independent around 1894. Additional portions of East Windsor Township were annexed in 1913, 1915 and 1927. The traditional explanation is that the borough was named for John and Mary Hight, who established a tavern in the area in the 1750s.
According to the United States Census Bureau, the borough had a total area of 1.27 square miles (3.28 km2), including 1.23 square miles (3.19 km2) of land and 0.03 square miles (0.09 km2) of water (2.60%).
The borough is an independent municipality surrounded entirely by East Windsor Township, making it part one of 21 pairs of "doughnut towns" in the state, where one municipality entirely surrounds another.
Hightstown is at the central-most point of New Jersey and is roughly equidistant from Philadelphia and New York City.
According to the A. W. Kuchler U.S. potential natural vegetation types, Hightstown, New Jersey would have an Appalachian Oak (104) vegetation type with an Eastern Hardwood Forest (25) vegetation form.
According to the Köppen climate classification system, Hightstown, New Jersey has a hot-summer, wet all year, humid continental climate (Dfa). Dfa climates are characterized by at least one month having an average mean temperature ≤ 32.0 °F (≤ 0.0 °C), at least four months with an average mean temperature ≥ 50.0 °F (≥ 10.0 °C), at least one month with an average mean temperature ≥ 71.6 °F (≥ 22.0 °C), and no significant precipitation difference between seasons. During the summer months, episodes of extreme heat and humidity can occur with heat index values ≥ 100 °F (≥ 38 °C). On average, the wettest month of the year is July which corresponds with the annual peak in thunderstorm activity. During the winter months, episodes of extreme cold and wind can occur with wind chill values < 0 °F (< -18 °C). The plant hardiness zone is 7a with an average annual extreme minimum air temperature of 0.0 °F (-17.8 °C).