Cliffside Park is a borough in Bergen County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 23,594, reflecting an increase of 587 (+2.6%) from the 23,007 counted in the 2000 Census, which had in turn increased by 2,614 (+12.8%) from the 20,393 counted in the 1990 Census.
Cliffside Park was formed based on the results of a referendum held on January 15, 1895, from portions of Ridgefield Township at the start of the second year of the Boroughitis phenomenon then sweeping through Bergen County.
U.S. Senator Frank Lautenberg currently resides in the borough. Cliffside Park was also home to the former Palisades Amusement Park.