Delaware Township is a township in Hunterdon County, New Jersey, United States. Part of the township is on the Hunterdon Plateau, while the southern portions are in the Amwell Valley. As of the 2010 United States Census, the township's population was 4,563, reflecting an increase of 85 (+1.9%) from the 4,478 counted in the 2000 Census, which had in turn declined by 34 (-0.8%) from the 4,512 counted in the 1990 Census. The historic community of Sergeantsville is located within Delaware Township, as is the Unincorporated community of Raven Rock. Other communities within the township are Croton, Locktown, Rosemont and Sand Brook.
Delaware was incorporated as a township by an Act of the New Jersey Legislature on April 2, 1838, from a portion of a larger municipality then known as Amwell Township (now defunct). Historian and cartographer John P. Snyder has erroneously stated that a referendum was held on that date, but there was in fact no referendum and the people of Amwell knew nothing about the division until after the Legislature passed the bill. A portion of the township was taken to form Stockton borough (April 14, 1898).
The township was first settled in the early 18th century by Colonel John Reading (1657–1717), who was instrumental in the creation of Amwell Township in 1708 and also worked for the creation of Hunterdon County in 1714. The Township adjoins the Delaware River on the southwestern portion of Hunterdon County. The state's lone surving historic covered bridge crosses the Wickecheoke Creek between Sergeantsville and Rosemont. The Delaware and Raritan Canal parallels the Delaware River along the southern border of the township. Sergeantsville is at the township's center and includes the municipal building, local public school and Post Office. A "Thanksgiving in the Country" offers a tour of notable homes in Sergeantsville, which raises funds for the Facial Reconstruction Unit of the Children's Hospital of Philadelphia.