Statistics for occurrence #1 of “Potomac river” in chapter 1.1 of Southern Historical Society Papers, Volume 20.:

...anding officers at New York, Newport, New London, Boston and Portland, Maine, to the same effect. Admiral Dalhgren is busy at Washington having twenty-four canal boats laden with stone to close the Potomac river . General McClellan on March 9th sends a telegram to General Wool, at Fort Monroe, in which, foreseeing the necessity of evacuating Newport News in the event the Merrimac gains possession of the R...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Potomac River (United States) 286 0 0 0 0 user votes
Potomac River (Maryland, United States) 2 0 0 0 0 user votes
Potomac River (Maryland, United States) 2 0 0 0 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.