As of the census of 2000, there were 18,560 people, 8,565 households, and 4,607 families residing in the city. The population density was 335.1 people per square mile (129.4/km). There were 9,480 housing units at an average density of 171.2 per square mile (66.1/km). The racial makeup of the city was 96.21% White, 0.50% Black or African American, 0.48% Native American, 1.35% Asian, 0.01% Pacific Islander, 0.16% from other races, and 1.3% from two or more races. 0.86% of the population were Hispanic or Latino of any race.