Ionia County, Michigan  Ionia County is a county located in the U.S. state of Michigan. As of the 2010 census, the population was 63,905. The county seat is Ionia. The Ionia County Courthouse was designed by Claire Allen, a prominent southern Michigan architect. Ionia County is part of the Grand Rapids-Kentwood, MI Metropolitan Statistical Area. The county is named for Ionia, a historic area of Greece. It was defined by act of the Territorial Legislature in 1831, and was organized in 1837. According to the US Census Bureau, the county has a total area of , of which is land and (1.5%) is water. As of the 2000 census, there were 61,518 people, 20,606 households, and 15,145 families residing in the county. The population density was 107 people per square mile (41/km²). There were 22,006 housing units at an average density of 38 per square mile (15/km²). The racial makeup of the county was 91.96% White, 4.56% Black or African American, 0.56% Native American, 0.32% Asian, 0.01% Pacific Islander, 1.04% from other races, and 1.55% from two or more races. 2.78% of the population were Hispanic or Latino of any race. 29.0% were of German, 14.7% American, 11.6% English, 8.9% Irish and 5.3% Dutch ancestry, 96.3% spoke English and 2.6% Spanish as their first language. There were 20,606 households out of which 38.10% had children under the age of 18 living with them, 58.70% were married couples living together, 10.10% had a female householder with no husband present, and 26.50% were non-families. 21.90% of all households were made up of individuals and 8.90% had someone living alone who was 65 years of age or older. The average household size was 2.70 and the average family size was 3.15. The county's population spread included 26.90% under the age of 18, 11.50% from 18 to 24, 31.00% from 25 to 44, 20.50% from 45 to 64, and 10.00% who were 65 years of age or older. The median age was 33 years. For every 100 females, there were 115.20 males.