Umfula wasePotomac uhamba ngamamitha angaphezu kwangu-383 ukusuka eFafafax Stone, eNtshonalanga Virginia kuya ePot Lookout, eMaldin. Lithinta abantu abangaphezu kwezigidi ezingu-6 abahlala ngaphakathi emanzini ase-Potomac, indawo eyi-14,670-square-mile lapho amanzi egeleza khona emlonyeni womfula. Leli mephu libonisa indawo yomfula kanye nomhlaba wayo omanzi ohamba ngezindawo ezihlukahlukene zezifundazwe ezihlanganisa i-Appalachian Plateau, i-Ridge & Valleys, i-Blue Ridge, iPiedmont, ne-Coastal Plain.
I-stem eyinhloko kanye nawo wonke amanani amakhulu amakhulu ama-12,878.8 amamitha okwenza uMfula iPotomac ube ngowama-21 ngobukhulu e-United States. Izindawo eziyinhloko zomfula wasePotomac yiNyakatho Yegatsha, uMfula iSavage, iNingizimu Yegatsha, iCacapon, i-Shenandoah, i-Antietam Creek, uMfula iMonocacy noMfula i-Anacostia. I-potomac ingena e- Chesapeake Bay emfuleni.