Rosenhayn is an unincorporated community and census-designated place located within Deerfield Township, in Cumberland County, New Jersey, United States. It is part of the Vineland-Millville- Bridgeton Primary Metropolitan Statistical Area for statistical purposes. As of the 2010 United States Census, the CDP's population was 1,098.Rosenhayn was founded as a Jewish agricultural colony and the 1898 Rosenhayn synagogue is one of the fewer than 100 surviving nineteenth century synagogue buildings in the United States.