The city was incorporated as a first-class city on May 20, 1960, making it one of the youngest communities in Johnson County. Its initial population was 28,085 and was bounded by Antioch Road (West), 107th Street (South), Chadwick (East) and I-35 (North). In 1960 the population was 28,085 with incorporated. By 1990 the population was 111,790 and in 1995 the incorporated land area was . Since 1995, the population has since grown to over 173,000 in 2008 with of land area. Overland Park is now the second most populous city in Kansas.
In early 2008, the city council voted to annex an additional south of existing city limits. The annexation went into effect March 10. After the annexation, the city spans nearly the entire distance between the northern and southern borders of Johnson County.
As of the census of 2000, there were 149,080 people, 59,703 households, and 39,702 families residing in the city. The population density was 2,627.0 people per square mile (1,014.3/km²). There were 62,586 housing units at an average density of 1,102.9/sq mi (425.8/km²). The racial makeup of the city was 90.65% White, 2.55% African American, 0.27% Native American, 3.83% Asian, 0.03% Pacific Islander, 1.24% from other races, and 1.43% from two or more races. 3.77% of the population were Hispanic or Latino of any race.
There were 59,703 households out of which 33.9% had children under the age of 18 living with them, 56.8% were married couples living together, 7.4% had a female householder with no husband present, and 33.5% were non-families. 27.4% of all households were made up of individuals and 7.7% had someone living alone who is 65 years of age or older. The average household size was 2.47 and the average family size was 3.06.
In the city the population was spread out with 26.2% under the age of 18, 7.0% from 18 to 24, 32.5% from 25 to 44, 23.0% from 45 to 64, and 11.4% who were 65 years of age or older. The median age was 36 years. For every 100 females there were 93.8 males. For every 100 females age 18 and over, there were 90.1 males.
The median income for a household in the city was $62,116, and the median income for a family was $77,176. Males had a median income of $52,072 versus $34,186 for females. The per capita income for the city was $32,069. 3.2% of the population and 2.1% of families were living below the poverty line, including 2.9% of those under the age of 18 and 3.5% of those 65 and older.
The Deanna Rose Children's Farmstead, a 12-acre, free attraction, is among the top 10 tourist destinations in the Kansas City area. It has more than 200 animals, hay rides, fishing pond, early 1900s century school house and more. It was recognized in August 2008 as the top "family" attraction in Kansas City by the Nickelodeon Channel.
Overland Park has begun construction on a 12-field tournament-quality soccer complex. It is expected to open for play in September, 2009. All the fields will have synthetic turf and lights. It will have an irrigation system to cool the turf on hot days.
The city is also the headquarters for YRC Worldwide, local telecommunications carrier Embarq, restaurant chain Applebee's, and the employee-owned Black & Veatch Corporation. The Shawnee Mission, Blue Valley, Spring Hill and Olathe school districts also employ several thousand people in the city.
The Johnson County Library serves the city. Overland Park is the location of several branch institutions: