 In terms of ancestry, 28.3% were German, 23.0% were Irish, 12.7% were Italian, 9.4% were Polish, 8.6% were English, 7.1% were Norwegian, and 3.0% were American.Of the 18,546 households, 38.6% had children under the age of 18 living with them, 57.8% were married couples living together, 9.7% had a female householder with no husband present, 27.6% were non-families, and 22.5% of all households were made up of individuals.The average household size was 2.69 and the average family size was 3.16.