Mercer County is a county located in the U.S. state of New Jersey. Its county seat is Trenton, also the state capital, prompting its nickname The Capital County. Mercer County alone constitutes the Trenton–Princeton metropolitan statistical area and is considered part of the New York combined statistical area by the U.S. Census Bureau, but also directly borders the Philadelphia metropolitan area and is included within the Federal Communications Commission's Philadelphia Designated Media Market Area. The county is part of the Central Jersey region of the state.
Ewing Township is a township in Mercer County, in the U.S. state of New Jersey. The township falls within the New York metropolitan area as defined by the U.S. Census Bureau. It borders the Philadelphia metropolitan area and is part of the Federal Communications Commission's Philadelphia Designated Market Area. As of the 2020 United States census, the township's population was 37,264, its highest decennial count ever and an increase of 1,474 (+4.1%) from the 35,790 recorded at the 2010 census, which in turn reflected an increase of 83 (+0.2%) from the 35,707 counted in the 2000 census.
Hopewell is a borough in Mercer County, in the U.S. state of New Jersey. Centrally located within the Raritan Valley region, this historical settlement is an exurban commuter suburb of New York City in the New York metropolitan area as defined by the United States Census Bureau. As of the 2020 United States census, the borough's population was 1,918, a decrease of 4 (−0.2%) from the 2010 census count of 1,922, which in turn had reflected a decline of 113 (−5.6%) from the 2,035 counted at the 2000 census.
Hopewell Township is a township in Mercer County, in the U.S. state of New Jersey. Located at the cross-roads between the Delaware Valley region to the southwest and the Raritan Valley region to the northeast, the township considered an exurb of New York City in the New York metropolitan area as defined by the United States Census Bureau, while also directly bordering the Philadelphia metropolitan area, being a part of the Federal Communications Commission's Philadelphia Designated Market Area. As of the 2020 United States census, the township's population was 17,491, its highest decennial count ever and an increase of 187 (+1.1%) from the 2010 census count of 17,304, which in turn reflected an increase of 1,199 (+7.4%) from the 16,105 counted in the 2000 census.
Princeton Junction is an unincorporated community and census-designated place (CDP) located within West Windsor township, Mercer County, in the U.S. state of New Jersey. As of the 2020 census, the CDP's population was 2,475.
Kingston is an unincorporated community and census designated place (CDP) along the border of South Brunswick Township in Middlesex County and Franklin Township in Somerset County, and also located relatively near Princeton in Mercer County in the U.S. state of New Jersey. The historic settlement is in the Raritan Valley region, located along the course of the Millstone River. As of the 2020 census, the CDP's population was 1,581, of which 1,272 were in South Brunswick Township and 309 in Franklin Township.
Franklin Township is a township in Somerset County, in the U.S. state of New Jersey. It is centrally located in the Raritan Valley region, within the New York Metropolitan Area. As of the 2020 United States census, the township's population was 68,364, an increase of 6,064 (+9.7%) from the 2010 census count of 62,300, which in turn reflected an increase of 11,397 (+22.4%) from the 50,903 counted in the 2000 census. The township was the state's 19th most-populous municipality in 2020, after being ranked 22nd in 2010.
Blackwells Mills is an unincorporated community and census-designated place (CDP) located in Franklin Township in Somerset County, in the U.S. state of New Jersey. As of the 2010 U.S. census, the CDP's population was 803.
Titusville is an unincorporated community and census-designated place (CDP) in Hopewell Township, Mercer County, in the U.S. state of New Jersey. As of the 2020 census, the population was 633. The area includes a post office with its own ZIP Code (08560), several restaurants, gas stations, a firehouse, and a small cluster of homes. Washington Crossing State Park, dedicated to George Washington's crossing of the Delaware River in 1776, is adjacent to the community.
Griggstown is an unincorporated community and census-designated place (CDP) located within Franklin Township, in Somerset County, in the U.S. state of New Jersey. As of the 2010 United States Census, the CDP's population was 819. The area was first settled around 1733. The Millstone River and the Delaware and Raritan Canal both flow through Griggstown.
Delaware is an unincorporated community and census-designated place (CDP) located along the Delaware River within Knowlton Township in Warren County, New Jersey. It was created as part of the 2010 United States Census. As of the 2010 Census, the CDP's population was 150. The area is served as United States Postal Service ZIP Code 07833.
Yardville is an unincorporated community and census-designated place (CDP) in Hamilton Township, Mercer County, New Jersey, United States. As of the 2020 United States census, the CDP's population was 6,965. Before the 2010 census, the area was part of the Yardville-Groveville CDP.
Groveville is an unincorporated community and census-designated place (CDP) located within Hamilton Township, in Mercer County, in the U.S. state of New Jersey. As of the 2020 census, the CDP's population was 3,106. Before the 2010 Census, the area was part of the Yardville-Groveville CDP.
Roebling is an unincorporated community and census-designated place (CDP) located within Florence Township, in Burlington County, in the U.S. state of New Jersey, that was established as part of the 2010 United States census. As of the 2000 United States census, the CDP was combined as Florence-Roebling, which had a total population of 8,200. As of the 2010 Census, the Florence-Roebling CDP was split into its components, Florence and Roebling. As of the 2010 Census, the population of the Florence CDP was 4,426.
Mercerville is an unincorporated community and census-designated place (CDP) located within Hamilton Township, in Mercer County, in the U.S. state of New Jersey. As of the 2020 census, the CDP's population was 13,447. Until after the 2000 census, the area was part of the Mercerville-Hamilton Square CDP. For the 2010 Census it was split into two CDPs, Mercerville and Hamilton Square.
Hamilton Square is an unincorporated community and census-designated place (CDP) located within Hamilton Township, in Mercer County, in the U.S. state of New Jersey, that is the site of a historic colonial village. Until the 2000 census the area was part of the Mercerville-Hamilton Square CDP, which was split into two CDPs as of 2010: Mercerville and Hamilton Square.
Weston is an unincorporated community and census-designated place (CDP) located in Franklin Township, in Somerset County, in the U.S. state of New Jersey. As of the 2010 United States Census, the CDP's population was 1,235.
Cream Ridge is an unincorporated community and census-designated place (CDP) in Upper Freehold Township, Monmouth County, New Jersey, United States. As of the 2020 census, the first one for which Cream Ridge was listed, the population was 630.
Renaissance at Monroe is a planned community and census-designated place (CDP) in Monroe Township, Middlesex County, New Jersey, United States. It was first listed as a CDP in the 2020 census with a population of 637.
Robbinsville Center is a census-designated place (CDP) located within Robbinsville Township in Mercer County, in the U.S. state of New Jersey. As of the 2020 census, it had a population of 3,164. Prior to 2020, the CDP was known as Robbinsville, with a population of 3,041 at the 2010 census. The area is served as United States Postal Service ZIP Code 08691.
United States 
New Jersey 
