Statistics for occurrence #1 of “Rapidan” in alphabetic letter O, entry group 2, entry on-to-richmond- of Harper's Encyclopedia of United States History:

...by a quick and skilful movement, while Meade was detained at Manassas Gap by a heavy skirmish, dashed through Chester Gap, and, crossing the Rappahannock, took a position between that stream and the Rapidan . For a while the opposing armies rested. Meade advanced cautiously, and at the middle of September he crossed the Rappahannock, and drove Lee beyond the Rapidan, where the latter took a strong de...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Rapidan (Virginia, United States) 580 6 4 0 0 user votes
Rapidan (Louisiana, United States) 2 0 0 0 0 user votes
Rapidan (Minnesota, United States) 0 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.