Hillsdale, New Jersey

Hillsdale is a borough in the northern portion of Bergen County, in the U.S. state of New Jersey, within the New York City metropolitan area. As of the 2020 United States census, the borough's population was 10,143, a decrease of 76 (−0.7%) from the 2010 census count of 10,219, which in turn reflected an increase of 132 (+1.3%) from the 10,087 counted in the 2000 census.

The populated area today known as Hillsdale took form in the mid-to-late 19th century as land speculators, led by David P. Patterson, developed subdivisions to profit from the coming of the Hackensack and New York Railroad (later New Jersey and New York Railroad). The area was incorporated as Hillsdale Township on March 25, 1898, from portions of Washington Township, which had, in turn, been set off from Harrington Township in 1840. Portions of the township were taken on April 30, 1906, to create the township of River Vale. Hillsdale was reincorporated as a borough by an act of the New Jersey Legislature on March 2, 1923, subject to approval which came in a referendum held on April 24, 1923. The borough's name derives from its location in a "dale among the hills".