Clarksville, IA

 CLARKSVILLE, the largest village in the county [Butler County, Iowa], is situated on the Shell Rock River, 25 miles north-east of Cedar Falls, at which place is situated the Clarksville Institute, an institution of learning, fast gaining a reputation as one of the best institutions in the State. It contains two churches, Methodist and Presbyterian, also a lodge each of Masons and Good Templars. It has two general stores, two drug stores, one grocery, one flour mill and two saw mills. Population, 500.  (Hair's Iowa State Gazetteer..., 1865)