Okun Potomac lọ ni o ju 383 miles lati Fairfax Stone, West Virginia si Point Lookout, Maryland. O ni ipa lori awọn eniyan to ju milionu 6 lọ ti o wa laarin ibọn omi Potomac, agbegbe ti o wa ni 14,670-square-mile ni ibi ti omi ṣan si ẹnu ẹnu odò naa. Yi maapu n fihan ipo ti odo ati agbegbe ti o ni omi ti o wa ni ọpọlọpọ awọn ẹkun-ilu ti o wa pẹlu Plateau Abpalachian, Oke ati Awọn Valleys, Blue Blue, Piedmont, ati Plain Coastal.
Ifilelẹ akọkọ ni afikun gbogbo awọn alabojuto pataki ni 12,878.8 miles ṣiṣe Odudu Potomac 21st tobi ni United States. Awọn alakoso pataki ti Odoko Potomac ni eka ariwa, odò Savage, South Branch, Cacapon, Shenandoah, Antietam Creek, Ododo Monocacy, ati odò Anacostia. Potomac n wọ inu Chesapeake Bay ni ibẹrẹ.