As part of its mission to provide navigational aids for the entire country, the U.S. Coast Survey published charts at various scales. Some covered small geographical areas, such as harbors. Others, such as this one showing the approaches to Boston Bay, covered larger lengths of the coast line.
Published at a scale of 1:80,000, it depicted the Massachusetts coast line from Cape Ann to Scituate. Like other Coast Survey charts, it included numerous depth soundings along the coast and in the primary harbors, as well as detailed topographic information about a mile inland from the shoreline.