The population density was 798.4 people per square mile (308.4/km²). There were 4,292 housing units at an average density of 398.7 per square mile (154.0/km²). The racial makeup of the city was 88.84% White, 6.47% African American, 0.07% Native American, 3.55% Asian, 0.15% from other races, and 0.92% from two or more races. Hispanic or Latino of any race were 0.70% of the population. 15.5% were of German, 15.3% Italian, 11.1% Slovene, 8.8% Irish and 7.3% English ancestry according to Census 2000. There were 3,973 households out of which 20.9% had children under the age of 18 living with them, 49.2% were married couples living together, 7.4% had a female householder with no husband present, and 40.1% were non-families. 35.1% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older. The average household size was 2.16 and the average family size was 2.82. In the city the population was spread out with 18.1% under the age of 18, 7.1% from 18 to 24, 28.4% from 25 to 44, 27.9% from 45 to 64, and 18.4% who were 65 years of age or older. The median age was 43 years. For every 100 females, there were 91.5 males. For every 100 females age 18 and over, there were 90.0 males. The median income for a household in the city was $47,493, and the median income for a family was $60,397. Males had a median income of $47,190 versus $30,908 for females. The per capita income for the city was $26,688. About 1.7% of families and 3.4% of the population were below the poverty line, including 2.7% of those under age 18 and 2.7% of those age 65 or over. The city is served by the Willoughby-Eastlake City School District. Willoughby Hills has a public library, a branch of Willoughby-Eastlake Public Library. Two notable buildings in Willoughby Hills are the Squire's Castle in the Cleveland Metroparks' North Chagrin Reservation and the Louis Penfield House, a house designed by Frank Lloyd Wright.