Lincoln Park is a borough in Morris County, New Jersey, United States. As of the 2010 United States census, the borough's population was 10,521, reflecting a decline of 409 from the 10,930 counted i…Lincoln Park is a borough in Morris County, New Jersey, United States. As of the 2010 United States census, the borough's population was 10,521, reflecting a decline of 409 from the 10,930 counted in the 2000 Census, which had in turn declined by 48 from the 10,978 counted in the 1990 Census.