This polygon shapefile represents the unified school district boundaries in Illinois. School districts are geographic entities within which state, county, or local officials provide public educational services for the area's residents. The unified school districts are districts that provide education to children of all school ages. The elementary school districts provide education to the lower grade/age levels and the secondary school districts provide education to the upper grade/age levels. In general, where there is a unified school district, no elementary or secondary school district exists and where there is an elementary school district, the secondary school district may or may not exist. School districts are geographic entities within which state, county, or local officials provide public educational services for the area's residents. The U.S. Census Bureau obtains the boundaries and names for school districts from state officials. The U.S. Census Bureau first provided data for school districts in the 1970 census. For Census 2000, the U.S. Census Bureau tabulated data for three types of school districts: elementary, secondary, and unified. Each school district is assigned a five-digit code that is unique within state. School district codes are assigned by the Department of Education and are not necessarily in alphabetical order by school district name.This dataset is intended for researchers, students, and policy makers for reference and mapping purposes, and may be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analysis with other spatial data.