Neponset River and Dam at Mattapan Postcards Neponset River and Dam at Mattapan No. 394 Postcard. Caption on front: Neponset River and Dam at Mattapan, Mass. Postmarked Oct 19, 1906. On verso: Published by C.O. Tucker, Boston. Facebook Twitter Print Friendly Skills Dam, Dorchester, Mattapan, Neponset River Posted on November 22, 2022 ← Below the Falls, Mattapan Franklin Field →