which county is prospect park nj in
Prospect Park, New Jersey. Prospect Park is a borough in Passaic County, New Jersey, United States. As of the 2010 United States Census, the borough's population was 5,865, reflecting an increase of 86 (+1.5%) from the 5,779 counted in the 2000 Census, which had in turn increased by 726 (+14.4%) from the 5,053 counted in the 1990 Census.