Tewksbury Township is a township located in Hunterdon County, New Jersey and is located within the New York Metropolitan Area. As of the 2010 United States Census, the township's population was 5,993, reflecting an increase of 452 (+8.2%) from the 5,541 counted in the 2000 Census, which had in turn increased by 738 (+15.4%) from the 4,803 counted in the 1990 Census. The township is named after Tewkesbury, England, and the two established a sister city relationship in 2003.
The township was first mentioned as holding a township meeting on March 11, 1755, as having been formed partly from Lebanon Township, though the exact circumstances of its formation by charter are unknown. Tewksbury was incorporated as one of New Jersey's initial 104 townships by an Act of the New Jersey Legislature on February 21, 1798. Portions of the township have been take to form Califon borough (April 2, 1898). Portions of the township were acquired from Readington Township in 1832 and 1861, and portions were transferred to Clinton Township in 1871 and 1891.
The original settlers were of English extraction. However, a large German contingent settled in the area around 1749 and theirs became the strongest influence when Tewksbury became a township. The enclave of Oldwick, with a mixture of Victorian, Federal, New England and Georgian style homes is protected by historic legislation. Zion Lutheran Church in Oldwick (formerly New Germantown) is the oldest German Lutheran parish in New Jersey.
Oldwick is home to the Somerset Hills Handicapped Riding Center, a North American Riding for the Handicapped Association (NARHA) Premier Accredited Center for Therapeutic horseback riding.