Richwood is an unincorporated community and census-designated place located in Gloucester County, in the U.S. state of New Jersey, that is split between Harrison Township and Mantua Township. As of the 2020 United States census, the CDP’s population was 3,577, an increase of 118 from the 3,459 enumerated at the 2010 U.S. census. The community was once known as Mount Pleasant.