Rwizi rwePotomac rwunopfuura makiromita 383 kubva ku Fairfax Stone, West Virginia kuenda ku Point Point, Maryland. Inobata vanhu vanopfuura mamiriyoni matanhatu vanogara mukati meGungwa rePotomac, nzvimbo 14,670-square-mile nzvimbo iyo mvura inoyerera kumuromo kwerwizi. Iyi mepu inoratidza nzvimbo yerwizi uye nzvimbo yaro yakadzika inotenderera kune dzimwe nzvimbo dzakasiyana-siyana dzegungwa dzinosanganisira Appalachian Plateau, Ridge & Valleys, Blue Ridge, Piedmont, uye Coastal Plain.
Iyo tsinde huru pamwe nemitengo mikuru mikuru 12,878.8 makiromita ichiita kuti Rwizi rwaPotomac rukuru rwe21 muUnited States. Mitsara mikuru yeRwizi rwePotomac ndiNorth Branch, Savage River, South Branch, Cacapon, Shenandoah, Antietam Creek, Rwizi Monocacy, uye Anacostia River. Potomac inopinda muCheesapeake Bay nechokumusoro.