Before the United States became a nation, Prince George’s County extended all the way from the Washington, D.C. line to the mountains. Problem was, prominent landowners who were settling farther and farther north and west, were finding it difficult to reach the Prince George’s courthouse. In 1748, Frederick County was created, but it too covered a tremendous amount of land and needed to be divided into thirds 18 years later. The lower section of Frederick County became Montgomery County and the upper section became Washington County.