Brownstown has three separate but connected segments due to the incorporation of the cities of Flat Rock, Rockwood, and Woodhaven in the early 1960s.

The area eventually fell into hands of the British and finally came under American rule in the 18th century.

The original 43-square-mile (110 km2) area of land south of Detroit was designated a township by the Michigan Territorial Council on April 5, 1827, when Moses Roberts was elected its first supervisor.

[6] Research from local historians has found that the township was named for Adam Brown, who was kidnapped by the Wyandot Indians.

Brown was raised by the Wyandots, married a native woman, and grew to become a tribal leader.

As time passed, settlements spread out from the lakeshore to begin changing the swampy, sandhill countryside into productive farmland.

The southernmost point of the Detroit River is within the township, which leads to Lake Erie.

Brownstown shares a water boundary with Grosse Ile Township and across the international border with the city of Amherstburg in Ontario.

[9] The township is also home to the Chevrolet Volt Battery Pack Assembly Plant.