Mercer County /

Mercer County is a county located in the state of Ohio, United States. Its county seat is Celina and is named for Hugh Mercer, an officer in the American Revolutionary War. The Celina Micropolitan Statistical Area includes all of Mercer County. According to the U.S. Census Bureau, the county has a total area of 473 square miles (1,226 km²).463 square miles (1,200 km²) of it is land and 10 square miles (26 km²) of it (2.12%) is water. As of the census of 2000, there were 40,924 people, 14,756 households, and 11,022 families residing in the county. The population density was 88 people per square mile (34/km²). There were 15,875 housing units at an average density of 34 per square mile (13/km²). The racial makeup of the county was 98.44% White, 0.10% Black or African American, 0.26% Native American, 0.29% Asian, 0.02% Pacific Islander, 0.34% from other races, and 0.56% from two or more races. 1.15% of the population were Hispanic or Latino of any race. There were 14,756 households out of which 37.10% had children under the age of 18 living with them, 64.10% were married couples living together, 7.40% had a female householder with no husband present, and 25.30% were non-families.