Bennington County, Vermont: History
Bennington is the oldest county in Vermont still in existence, created by the first general assembly on March 17, 1778. Vermont was organized into two original counties, with Bennington in the west and Unity (a few days later renamed Cumberland) in the east. On February 16, 1781, Rutland County was created from Bennington County. On April 13, 1781, Bennington gained the gore east of the town of Bromley (now Peru) from Windham and Windsor Counties, now known as Landgrove.
From June 26, 1781, until February 23, 1782, Vermont attempted to annex part of New York east of the Hudson River (the so-called West Union); inhabitants in the area favored Vermont's township form of government, while Vermont hoped to gain bargaining power through expansion. New York did not lose control of the area. For almost seven months Bennington County overlapped part of Albany County, New York.
On February 27, 1787, Windham County gained the town of Stratton from Bennington County, On October 25, 1805, Rutland County gained from the county when the town of Mount Tabor gained from the town of Peru. The county gained from Rutland County when the town of Dorset gained a small area from the town of Mount Tabor on November 17, 1825.