Troy Grove is a village in LaSalle County, Illinois, United States. The population was 225 at the 2020 census, down from 250 at the 2010 census. It is part of the Ottawa, IL Micropolitan Statistical Area. Troy Grove is notable as the birthplace of Wild Bill Hickok and Kate Austin. It is home to the Wild Bill Hickok Memorial. The town also has another connection to the Wild West, as the last reported wild bison killed in Illinois happened near the town in 1837.