As of the census of 2000, there were 52,524 people, 23,079 households, and 12,970 families residing in the village. The population density was 11,173.4 people per square mile (4,314.8/km²). There were 23,723 housing units at an average density of 5,046.6/sq mi (1,948.8/km²). The racial makeup of the village was 68.78% White, 22.44% African American, 0.15% Native American, 4.15% Asian, 0.03% Pacific Islander, 1.63% from other races, and 2.82% from two or more races. Hispanic or Latino of any race were 4.52% of the population. 14.5% were of Irish, 11.3% German, 6.8% Italian and 5.5% English ancestry according to Census 2000. 88.1% spoke English and 4.2% Spanish as their first language.
There were 23,079 households, out of which 29.5% had children under the age of 18 living with them, 42.1% were married couples living together, 11.6% had a female householder with no husband present, and 43.8% were non-families. 37.0% of all households were made up of individuals and 8.6% had someone living alone who was 65 years of age or older. The average household size was 2.26 and the average family size was 3.06.
In the village the population was spread out with 24.2% under the age of 18, 6.7% from 18 to 24, 35.2% from 25 to 44, 24.4% from 45 to 64, and 9.5% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 86.9 males. For every 100 females age 18 and over, there were 82.2 males.
According to a 2007 estimate, the median income for a household in the village was $74,614, and the median income for a family was $103,840. Males had a median income of $51,807 versus $40,847 for females. The per capita income for the village was $36,340. About 3.6% of families and 5.6% of the population were below the poverty line, including 5.8% of those under age 18 and 7.9% of those age 65 or over.
Oak Park has a long history of encouraging and maintaining racial and ethnic diversity, much of which was started in conjunction with the 1966 Chicago Open Housing Movement. The village operates a Diversity Assurance Program within its housing programs department to ensure a stable, diverse, and integrated population. Years ago, Oak Park eliminated the use of "For Sale" signs in front of houses, widely considered one of the keys of success to maintaining the high diversity. However, this law was declared unconstitutional, being overturned by Linmark Associations, Inc. v. Township of Willingboro, 431 U.S. 85, Supreme Court of the United States, 1977. Justice Thurgood Marshall delivered the opinion of the Court.
Oak Park is accessible from Chicago by both Chicago Transit Authority Green and Blue line trains as well as Metra UP-West Line trains at Oak Park station. Service within Oak Park and to other suburbs is also provided by the suburban bus system Pace. It is also one of over 20 neighborhoods served by I-GO Cars.
The Eisenhower Expressway--formerly the Congress Expressway--is the primary highway between Chicago and Oak Park. Oak Park has its own street numbering system that is similar to, but distinct from, Chicago's system.
Oak Park has a rich tradition of bicycling. Augusta Boulevard through the village is part of the Grand Illinois Trail; the trailhead of the Illinois Prairie Path is less than a mile from Oak Park. It is considered one of the most progressive bicycle-friendly communities in the Chicago area and has a number of active cycle clubs and groups. Proximity to trails and the historic tree-lined streets of the community attract cyclists from throughout the region, many of whom arrive by the Chicago area's extensive public transportation system. Oak Park also has a small pedicab business, owned and operated by a local who provides guided tours and a taxi service with his bicycle pedicabs or rickshaws. There is also a free shuttle service which transports riders to most of the tourist attractions in the village .