Compiled from manuscript maps prepared by the U.S. Coast Survey in 1847 and updated to 1854, this was one of four maps that accompanied the first report of the Commissioners on Boston Harbor and the Back Bay. The other maps provided larger scale representations of Mystic River, South Bay, the Neponset River and parts of Dorchester Bay. One of the key features of these maps was the delineation of harbor commissioners' lines as defined for 1847, with proposed revisions for 1854. These lines defined how far wharves could extend from the shore, thus helping to define the city's expanding shoreline.