Brothersvalley Township was incorporated in 1771 and its largest borough, Berlin, laid out in 1784.[3] The area was settled by immigrants, mostly from Germany, and became a hotbed of the Whiskey Rebellion.The Beechdale Bridge was added to the National Register of Historic Places in 1980.At the 2000 census there were 4,184 people in 862 households, including 712 families, in the township.A small portion of State Correctional Institution – Somerset is in the township.