Oldwick is an unincorporated area within Tewksbury Township in Hunterdon County, New Jersey, United States. The area is served as United States Postal Service ZIP Code 08858. As of the United States 2000 Census, the population for ZIP Code Tabulation Area 08858 was 177. Oldwick was formerly known as New Germantown. It has a mixture of Victorian, Federal, New England and Georgian style homes, and is protected by historic legislation. Historic sites within Oldwick include Kline Farmhouse, Oldwick Historic District and the Taylor's Mill Historic District. Zion Lutheran Church in Oldwick was the oldest Lutheran parish in New Jersey. Justus Falckner of New York, the first Protestant clergyman ever ordained in America, led the worshipers at the founding ceremony on August 1, 1714. The noted German Lutheran pastor, Henry Melchior Muhlenberg, was a member of this congregation fom 1759 to 1760. Oldwick is the corporate headquarters of the A. M. Best rating agency, and is the location of Somerset Hills Handicapped Riding Center for therapeutic horseback riding.