[4] The Town of Marshall is in the southeastern part of the county and is located southwest of Utica.

The first settlers were the Brothertown Indians, a group of about 400 people formed from scattered remnants of tribes from New England and Long Island, led by Asa Dick and Samson Occom, who arrived around 1774.

The number of Brotherton Indians had dwindled by 1850, with some succumbing to alcoholism, and others selling their land and moving to Green Bay, Wisconsin.

[5] The first white settlers arrived in 1794 and settled in the higher regions, in Hanover and the west hills.

According to the United States Census Bureau, the town has a total area of 32.8 square miles (85 km2), all land.