Princeton Junction is an unincorporated community and census-designated place (CDP) located within West Windsor Township, in Mercer County, New Jersey, United States. As of the 2010 United States Census, the CDP's population was 2,465.
Following the mid-1860s relocation of the Camden & Amboy rail line from next to the Delaware & Raritan Canal to the present location of the Northeast Corridor, and the subsequent construction of a train station south of the intersection of Washington Road and the new rail line, a community called "Princeton Junction" developed. This community originally featured several farmhouses, a hotel, a general store, a feed mill, and several other businesses centered around the intersection of Station Drive & Washington Road, profiting off of access to other cities provided by the rail line.
The construction of the neighborhood of Berrien City (focused around Scott Avenue, Alexander Road, and Berrien Avenue) represented West Windsor's first planned development. Following the reconstruction of the Washington Road railroad bridge in 1939, the business center of the community shifted to the intersection of Washington Road and Cranbury Road, where a lumber yard, service station, liquor store, strip mall, several gas stations, and several more businesses operated for decades.
Following World War II,, the Princeton Junction population grew with the construction of residential developments such as Sherbrooke Estates, Windsor Chase, and Wellington Estates.
Princeton Junction is currently the proposed site of a "Transit Village" to be built northwest of the train station.
In October 2019, the Historical Society of West Windsor published an online museum exploring the history of West Windsor - including that of Princeton Junction.
According to the United States Census Bureau, the CDP had a total area of 1.853 square miles (4.801 km2), including 1.826 square miles (4.730 km2) of land and 0.027 square miles (0.071 km2) of water (1.48%).
Princeton Junction's name comes from the train station of the same name, now on the Amtrak and New Jersey Transit Northeast Corridor. The station is the junction between this main line and a spur served by the "Dinky" train, run by New Jersey Transit, to Princeton itself.
The 2010 United States Census counted 2,465 people, 921 households, and 696 families in the CDP. The population density was 1,349.8 inhabitants per square mile (521.2/km2). There were 940 housing units at an average density of 514.7 per square mile (198.7/km2). The racial makeup was 74.81% (1,844) White, 2.43% (60) Black or African American, 0.16% (4) Native American, 18.62% (459) Asian, 0.00% (0) Pacific Islander, 1.42% (35) from other races, and 2.56% (63) from two or more races. Hispanic or Latino of any race were 5.44% (134) of the population.
Of the 921 households, 35.0% had children under the age of 18; 68.6% were married couples living together; 5.4% had a female householder with no husband present and 24.4% were non-families. Of all households, 20.8% were made up of individuals and 11.5% had someone living alone who was 65 years of age or older.