Union Township is a civil township of Branch County in the U.S. state of Michigan. The population was 2,868 at the 2010 census.The village of Union City is the only incorporated municipality in the township. The only other settlement in the primarily agricultural township is the unincorporated community of Hodunk, situated on the boundary with adjacent Girard Township near the junction of Hog Creek and the Coldwater River. Hodunk is at 42°00′53″N 85°03′42″W. The FIPS place code is 38580.