As of the census of 2010, there were 238,136 people, 87,446 households, and 64,299 families in the county. The population density was 620/sqmi (239/km2). There were 87,446 housing units at an average density of 228/sqmi (87.9/km2). 39.4% were of German, 14.4% Irish, 13.0% Norwegian, and 9.9% Swedish ancestry. There were 87,446 households, out of which 38.6% had children under the age of 18 living with them, 60.6% were married couples living together, 9.5% had a female householder with no husband present, and 26.5% were non-families. 21.5% of all households were made up of individuals, and 7.3% had someone living alone who was 65 years of age or older. The average household size was 2.67 and the average family size was 3.14.