Duncan township was formed from the townships of Delmar, Charleston and Morris, in December 1873. Duncan is bounded on the north by the townships of Delmar and Charleston, on the east by Bloss and Morris, on the south by Morris, and on the west by Morris and Delmar. The discovery of coal in 1867 was the driving force behind the development of the Village of Antrim. The township has a total area of 19.8 miles. Current population is approximately 240. The township maintains 7 roads totaling approximately 7 miles.
Special thanks to Tri-Counties Genealogy and History by Joyce M. Tice for historical material