2011 Redistricting
The district covers parts of Cook County, as of the 2011 redistricting which followed the 2010 census. All or parts of Berwyn, Brookfield, Chicago, Cicero, Lyons and Melrose Park are included. The representatives for these districts will be elected in the 2012 primary and general elections, and the boundaries will become effective on January 5, 2013.
Read more about this topic: Illinois's 4th Congressional District