Allegheny Township is a township in Westmoreland County, Pennsylvania, United States. The population was 8,002 at the 2000 census. It is the northern most municipality of Westmoreland County. The municipality borders the townships of Buffalo, Harrison, Upper Burrell, and Washington; and the boroughs of Oklahoma, Vandergrift, Leechburg, West Leechburg, Lower Burrell, Freeport and Hyde Park.