As of the census of 2000, there were 31,365 people, 11,521 households and 8,917 families residing in the city. The population density was 2,537.5 people per square mile (979.8/km²). There were 11,934 housing units at an average density of 965.5/sq mi (372.8/km²). The racial makeup of the city was 91.20 percent White, 1.78 percent African American, 0.08 percent Native American, 2.28 percent Asian, 0.01 percent Pacific Islander, 3.46 percent from other races, and 1.18 percent from two or more races. Hispanic or Latino of any race were 8.90 percent of the population.
As of the 2000 census, there were 11,521 households out of which 36.9 percent had children under age 18 living with them, 69.9 percent were married couples, 5.8 percent had a female householder with no husband present and 22.6 percent were non-families. Nineteen-point-five percent of all households were made up of individuals and 9.3 percent had someone living alone who was 65-years-old, or older. The average household size was 2.71 people and the average family size was 3.09 people.
As of the 2000 census, in the city, the population was spread out with 27.0 percent under age 18, 4.6 percent from 18-to-24-years-old, 25.5 percent from 25-to-44-years-old, 27.8 percent from 45-to-64-years-old, and 15.1 percent who were 65-years-old, or older. The median age was 41-years-old. For every 100 females there were 95.9 males. For every 100 females age 18 and over, there were 92.5 males.
According to a 2007 estimate, the median income for a household in the city was $113,350, and the median income for a family was $137,703. Males had a median income of $83,121 versus $41,175 for females. The per capita income for the city was $55,331. About 2.3 percent of families and 3.8 percent of the population were below the poverty line, including 3.9 percent of those under age 18 and 3.1 percent of those age 65 or over.
The main highway in Highland Park is US-41, which connects Chicago to Milwaukee. Commuter rail is available at five Metra stations (Braeside, Ravinia Park, Ravinia, Highland Park, and Fort Sheridan) on the Union Pacific North Line, which begins in Chicago and terminates in Kenosha, Wisconsin. Pace also offers several bus routes. Boat launch facilities are available along Lake Michigan, and O'Hare International Airport is located approximately 20 miles (32 km) southwest.