Teaneck is a township in Bergen County, New Jersey, United States, and a suburb in the New York metropolitan area. As of the 2010 United States Census, the township's population was 39,776, reflecting an increase of 516 from the 39,260 counted in the 2000 Census, which had in turn increased by 1,435 from the 37,825 counted in the 1990 Census. As of 2010 it was the second-most populous among the 70 municipalities in Bergen County, behind Hackensack, which had a population of 43,010.
Teaneck was created on February 19, 1895, by an act of the New Jersey Legislature from portions of Englewood Township and Ridgefield Township, both of which are now defunct, along with portions of Bogota and Leonia. Independence followed the result of a referendum held on January 14, 1895, in which voters favored incorporation by a 46–7 margin. To address the concerns of Englewood Township's leaders, the new municipality was formed as a township, rather than succumbing to the borough craze sweeping across Bergen County at the time. On May 3, 1921, and again on June 1, 1926, portions of what had been Teaneck were transferred to Overpeck Township.