The boundary question surfaced in 1989 when school officials and fire departments started questioning the dividing line between the two counties.
Although Jefferson County was formed in 1801 from Loudoun County, the boundary line was never officially surveyed. The unofficial boundary separating the counties was the crest of the mountain.
Last week West Virginia Culture and History Commissioner Randall Reid-Smith presented Jefferson County officials a plaque ending the dispute.
Similar plaques were sent to Loudoun County officials and to the governor's of Virginia and West Virginia.