Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Mad River Township is one of the ten townships of Clark County, Ohio, United States. The 2000 census found 11,828 people in the township, 9,190 of whom lived in the unincorporated portions of the township. Statewide, the only other Mad River Township is located in Champaign County. The township is governed by a three-member board of trustees, who are elected in November of odd-numbered years to a four-year term beginning on the following January 1.