The Coastal Plain Swamp Sparrow (Melospiza georgiana nigrescens) is morphologically distinct, restricted to a narrowly-defined habitat type, and geographically isolated within the mid-Atlantic Coastal Plain. The breeding range has been considered to extend from the Nanticoke River in Maryland north to the Hudson River. We report a previously undocumented population near Warsaw, Virginia that extends the known range south and west into a region of the Chesapeake Bay with extensive tidal fresh and brackish marshes consistent with the habitat requirements of this form, but for which there has been no documented breeding. A broader investigation of occurrence within appropriate habitat seems warranted given the small global population size and uncertain status within the southern portion of its range.