Regular registration ends 27 days before the election, then grace period registration kicks in
March 23 – April 4, Early voting period
April 4, last day of grace period registration/address change*
April 7, Election Day
*If registering or changing address during grace period, must vote at time of registration
There is more detail on the Lake County Clerk’s site, including these 2 pages:
http://countyclerk.lakecountyil.gov/Resources/Documents/February_Calendar.pdf
http://countyclerk.lakecountyil.gov/ElectionInfo/Voter-Services/Pages/Voter-Registration.aspx
More detail is also available at the Cook County Clerk’s site:
http://www.cookcountyclerk.com/elections/DocumentLibrary/VoterInformationGuide_English_eBrochure.pdf