Allegany County, Maryland: History
The western part of Maryland (including the present Allegany County) was originally part of Prince George's County when that county was formed in 1696. This county included six current counties, and by repeated splitting, new ones were generated: Frederick from Prince George's in 1748; and Montgomery and Washington from Frederick in 1776.
Allegany County was formed in 1789 by the splitting of Washington County. At the time it was the westernmost county in Maryland, but a split in 1872 created Garrett County, the current westernmost county.
Prior to 1789, the Virginia Commonwealth claimed the area of present-day Garrett and Allegany Counties, of Maryland. A 1771–1780 map of Virginias counties, shows Hampshire County, but the Virginia State boundary has Hampshire outside that boundary line. When conducting genealogical research, it is possible to find tax records for Hampshire County, Virginia included in Maryland records, and Maryland records in Hampshire County... Hampshire County was formed in 1758 by the Virginia Commonwealth and at its founding, included the present day counties of Garrett and Allegany Counties in Maryland, and Hardy, Grant, Mineral, and part of Morgan Counties in what is now West Virginia.
In 1899, Theodore Roosevelt, then Governor of New York, passed through Allegany County on a four ½-hour “whistle stop” tour.