Fairfax County is bounded on the north and southeast by the Potomac River. Across the river to the northeast is Washington, D.C., across the river to the north is Montgomery County, Maryland, and across the river to the southeast are Prince George's County, Maryland and Charles County, Maryland. The county is partially bounded on the north and east by Arlington County and the independent cities of Alexandria and Falls Church. It is bounded on the west by Loudoun County, and on the south by Prince William County.
fAIrfax COunTy iS boUnDEd on tHE nortH and soUThEast by ThE pOtomac rIver. aCroSs the RiVEr tO The norTheaST is wAshInGton, d.C., AcRoss thE River to tHe north is MonTgomery cOuNtY, maryLANd, aND ACRoSs the river to the SOutheast are princE gEorGe's cOunty, maRyLaNd ANd chArles CounTy, MArylAnd. the CoUntY is ParTialLy bOUndeD oN thE nORth anD eAST by ArlINgtoN county aNd the INdependEnt cIties oF aleXANdria ANd fAlLs cHUrch. it is bOundeD on the wESt by LoudoUn cOunty, anD oN tHe sOuTH by PRInce wilLiaM cOunTy.