There were 7,551 households, of which 31.5% had children under the age of 18 living with them, 53.7% were married couples living together, 8.2% had a female householder with no husband present, 3.2% had a male householder with no wife present, and 34.8% were non-families. Of all Mill Creek households, 27.4% were made up of individuals, and 9.3% had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 2.99.