Blairstown is a township in Warren County, New Jersey, United States. As of the 2010 United States Census, the township's population was 5,967 reflecting an increase of 220 (+3.8%) from the 5,747 counted in the 2000 Census, which had in turn increased by 416 (+7.8%) from the 5,331 counted in the 1990 Census.
The area had been known as Smith's Mill and was later called Butts Bridge (variously spelled as "Butt's Bridge" and "Butts' Bridge"), named for a family that owned the eponymous crossing of the Paulins Kill.
Blairstown was incorporated as a township by an act of the New Jersey Legislature on April 14, 1845, from portions of Knowlton Township, based on the results of a referendum held that day. The township was named for John Insley Blair.
According to the United States Census Bureau, the township had a total area of 30.78 square miles (79.71 km2), including 29.89 square miles (77.41 km2) of land and 0.89 square miles (2.30 km2) of water (2.88%). The township is located in the Kittatinny Valley which is a section of the Great Appalachian Valley that stretches for 700 miles (1,100 km) from Canada to Alabama.
Blairstown CDP (with a 2010 Census population of 515) is an unincorporated community and census-designated place (CDP) located within the township.
Other unincorporated communities, localities and place names located partially or completely within the township include Blair Lake, Cedar Lake, Cooks Pond, Jacksonburg, Kalaroma, Lake Susquehanna, Mount Vernon, Paulina, Vail and Walnut Valley.
White Township borders the Warren County municipalities of Frelinghuysen Township, Hardwick Township, Hope Township and Knowlton Township.
The Township's economic data (as is all of Warren County) is calculated by the United States Census Bureau as part of the Allentown–Bethlehem–Easton metropolitan area which also includes Carbon County, Lehigh County and Northampton County counties in Pennsylvania.
The 2010 United States Census counted 5,967 people, 2,124 households, and 1,703 families in the township. The population density was 193.6 inhabitants per square mile (74.7/km2). There were 2,272 housing units at an average density of 73.7 per square mile (28.5/km2). The racial makeup was 96.03% (5,730) White, 1.12% (67) Black or African American, 0.12% (7) Native American, 1.14% (68) Asian, 0.00% (0) Pacific Islander, 0.45% (27) from other races, and 1.14% (68) from two or more races. Hispanic or Latino of any race were 3.79% (226) of the population.
Of the 2,124 households, 32.8% had children under the age of 18; 66.8% were married couples living together; 9.4% had a female householder with no husband present and 19.8% were non-families.