Cook County Historical GIS Data Portal
To locate the most current data sources please visit Cook Central, our main Geographic Information Systems (GIS) site.
This site is Cook County's repository for historical GIS data. Cook County makes historical data available to the public in an effort to improve transparency. While this data is no longer current, it can still be used as a resource for historical analysis and mapping. These historical datasets focus on social information, environmental information, boundaries and districts, transportation, places of interest, and property information. Most of the data can be made available in shapefile format. Please contact Cook County GIS if you have GIS-related questions. If you are looking for historical imagery and parcels, they are located on the main Cook Central site.
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Cook County is divided into many different taxing districts and political boundaries. These taxing districts determine the types of services residents receive and the political boundaries determine which official represents constituents in their district.
While containing the City of Chicago, a densely populated urban metropolitan area of over 2.7 million residents, Cook County also contains nearly 70,000 acres of open space. In 1914, Cook County established a forest preserve system to preserve and protect public lands.
Cook County includes many types of facilities and resources, including Cook County Government buildings, other government facilities, parks, hospitals, schools, courts, libraries, cemeteries, and more.
Cook County maintains and manages records for 1.8 million property parcels. About 30-50 thousand parcel edits are made each year. Approximately $12 billion in property taxes are generated annually.
Established in 1913 by the State of Illinois, the Cook County Department of Transportation and Highways has maintenance responsibilities for 1,426 lane miles of pavement, 132 bridges, 360 traffic signals and seven pumping stations from four maintenance facilities.
Cook County also provides historical and current non-GIS data. On the Open Data portal, various departments publish data on economic development, public health, courts, finance and administration, etc. The data is presented tabularly and can be exported in various formats.