The Public Land Survey System (PLSS) is the way land in the United States is subdivided, it forms the foundation of Cook County's cadastral system for identifying and locating land records. Tax parcels are identified using township and section notation, in a modified format. The PLSS serves as a way for users to navigate the parcel geodatabase. This PLSS feature data set is intended to correspond to tax pages on the Cook County Tax Maps. They should not be used for measurement or surveyor purposes. In addition, the parcel attributes PINA (area/township) and PINSA (subarea/section) do not necessarily correspond to the PLSS township and section polygon in which a given parcel resides. The PLSS data is modeled as a single composite network coverage that encompasses townships (area), sections (subarea), quarter sections, and half quarter section. Tax map pages, which typically correspond to half quarter sections (in an east-west split), are modeled as a region subclass in the LANDFABRIC layer. If an indigenous people's reserve was present on the tax map, it was digitized to create subpolygons of the half-quarter section, and those polygons were attributed with the name of the reserve. Within this PLSS data set, a half-quarter section is the smallest polygon unit, except in cases where an Indigenous People's Reserve line is present. The cadastral data for Cook County have previously not been digital nor automated. This project is the initial automation for this information. This database was designed to represent a continuous, non-overlapping spatial database accounting for all land area in Cook County.The PLSS is updated as needed.

Cook County GIS Department map of municipal boundaries in Cook Cook County, Illinois in PDF format. Includes major streets, waterbodies, rail, Cook County Forest Preserve, and municipal boundaries.

Forest Preserve District of Cook County boundaries. To view or use these shapefiles, compression software and special GIS software, such as ESRI ArcGIS, is required.

DuPage County, IL boundary.

Geospatial data about Cook County, Illinois ZIP Code Boundary. Export to CAD, GIS, PDF, CSV and access via API.

Polygon vector map data covering city boundaries for Chicago, Illinois, containing 1 feature.

Boundary GIS (Geographic Information System) data is spatial information that delineates the geographic boundaries of specific geographic features..

This data typically includes polygons representing the outlines of these features, along with attributes such as names, codes, and other relevant information.

Boundary GIS data is used for a variety of purposes across multiple industries, including urban planning, environmental management, public health, transportation, and business analysis.

Available for viewing and sharing as a map in a Koordinates map viewer. This data is also available for export to DWG for CAD, PDF, KML, CSV, and GIS data formats, including Shapefile, MapInfo, and Geodatabase.

​

Cook County GIS Department map of Cook County Commissioner Districts in PDF format. Includes major streets, waterbodies, rail, and Cook County Commissioner District boundaries.

Shapefile showing boundaries of townships in 1851. Features based upon modern GIS maps of township boundaries and then adjusted to match information from Flower and Mendel's 1861 property map of Cook County, Illinois.

Cook County GIS Department map of Cook County Commissioner District 14 in PDF format. Includes major streets, waterbodies, rail, and Cook County Commissioner District boundaries.

The purpose of this dataset is to indicate the boundary of each park in Cook County, Illinois.

Hydrographic data was collected for all of Cook County. Significant flowing and standing water features that were visible on the aerial photography were stereocompiled from 1998 aerial photography. The hydrographic midline data set represents, as a single line, the interpreted midline of flowing water features as seen on the aerial photography. The hydrographic midline data layer is used to show the location of the midline of natural drainage features, and is connected to polygonal (standing) hydrographic features such as lakes and ponds. The midline data layer also includes drainage features less than five feet in width, which were not included in the polygon hydrography data set. Midlines were added to water bodies such as double-line rivers to maintain the linear connectivity of the hydrographic network. Where the course of linear features (such as streams and rivers) in the hydrographic midline layer could not be compiled photogrammetrically due to being obscured by other features (such as vegetation or shadows), the obscured line segment was coded as "interpreted". In some cases, a flowing water feature may have run through an underground drain or culvert or its course otherwise obscured from view on the aerial photography. For such cases, in order to maintain linear connectivity of the features, its path was also interpreted and coded as such. Some hydrographic data was provided by the City of Chicago and incorporated into this data layer. These hydrographic data layers are modeled and stored as a network coverage containing polygons and/or lines. This midline data layer was created out of need by Cook County to develop a hydrographic layer in which water features are represented as single lines. The intended primary use of this data layer is for small-scale mapping and networking. The hydrographic midline layer was intersected with the street midline and railroad data layers to create nodes in the coverage model. It was also intersected with the bridge polygon data layer. Where hydrographic midline segments fall within a bridge polygon, they have been given a grade separation code of zero (0) to indicate the water level is technically "at grade". Hydrographic attributes include feature name, tax map name, and type. The primary source of the attribute information was the Cook County Highway Department database. Hydrographic names and alias IDs are linked to lookup tables based on the hydrographic name ID attribute.

Neighborhood polygons used by the Cook County Assessor's Office for valuation and reporting. These neighborhoods are specific to the Assessor. They are intended to represent homogenous housing submarkets, NOT Chicago community areas or municipalities. These neighborhoods were reconstructed from individual parcels using spatial buffering and simplification. The full transformation script can be found on the Assessor's GitHub. Read about the Assessor's 2025 Open Data Refresh.

Cook County GIS Dept map of Commissioner District 10

Cook County GIS Dept map of Niles, Evanston, Rogers Park & Jefferson Townships in a pdf format. Includes streets and municipalities.

Cook County GIS Department map of Cook County Commissioner District 8 in PDF format. Includes major streets, waterbodies, rail, and Cook County Commissioner District boundaries.

The purpose of this dataset is to indicate the boundary of each Commissioner district in Cook County, Illinois. These boundaries are based off of Census 2010 geographies, were adopted June 2012 and went into effect in December 2014 following the County Commissioner elections.

These data are high-resolution bathymetry (riverbed elevation) in LAS format, generated from the August 22-24, 2022, hydrographic survey of the Chicago Sanitary and Ship Canal (CS&SC) and sections of the Chicago River and North Branch Chicago River in Cook County, Illinois. The survey extends from the Cook County line near Interstate 355 in the southwest upstream to the Chicago Harbor Lock on the Chicago River in the northeast, and northward on the North Branch Chicago River to the North Avenue Turning Basin in the north. Hydrographic data were collected using a high-resolution multibeam echosounder mapping system (MBMS), which consists of a multibeam echosounder (MBES) and an inertial navigation system (INS) mounted on a marine survey vessel. Data were collected as the vessel traversed the river along overlapping longitudinal survey lines distributed throughout the reach. Data collection software integrated and stored the depth data from the MBES and the horizontal and vertical position and attitude data of the vessel from the INS in real time. Data processing required specialized computer software to extract bathymetry data from the raw data files and to summarize and map the information. The bathymetry dataset is provided in American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format with metadata as ChicagoSSCanal_bathymetry_2022-08.las. The LAS format is a standardized binary format for storing 3-dimensional point cloud data and point attributes along with header information and variable length records specific to the data. Data points are stored as a 3-dimensional data cloud as a series of x (longitude), y (latitude), and z (elevation) points. Please refer to http://www.asprs.org/Committee-General/LASer-LAS-File-Format-Exchange-Activities.html for additional information.

Cook County GIS Department map of Cook County Commissioner District 17 in PDF format. Includes major streets, waterbodies, rail, and Cook County Commissioner District boundaries.

The purpose of this dataset is to indicate the boundary of each school in Cook County, Illinois.

Historical data. For current boundaries see https://datacatalog.cookcountyil.gov/id/vx2u-6dxj. The purpose of this dataset is to indicate the boundary of each Commissioner district in Cook County, Illinois. These boundaries are based off of Census 2000 geographies and were in effect until the December 2014 County Commissioner elections.