The Clerk's downtown office (69 W. Washington, Fifth Floor, Chicago) and the five suburban Cook County courthouse mini-centers will stay open until 8 p.m.  Chicago Board of Elections will be open until 12am. Locations listed below: 

Voters can register for the first time or update their registration information: (Click Here for Article Source)
Downtown Chicago (Until Midnight)

Chicago Board of Elections (Sixth Floor) 
69 W. Washington St.
Chicago, IL 60602 

Call: (312) 603-0900

Downtown Chicago (Until 8pm)

George W. Dunne Cook County Administration Building (Clerk's Office on the 5th Floor) 
69 W. Washington St.
Chicago, IL 60602 

Call: (312) 603-0900

North Suburbs - Skokie (Until 8pm)
5600 W. Old Orchard Road (Room 149)
Skokie, IL 60077 

Call: (847) 470-7233


Northwest Suburbs - Rolling Meadows (Until 8pm)
2121 Euclid Ave. (Room 238)
Rolling Meadows, IL 60008

Call: (847) 818-2850


West Suburbs - Maywood (Until 8pm)
1311 Maybrook Square, Room 104 
Maywood, IL 60153
 

Call: (708) 865-6010


South Suburbs - Markham (Until 8pm)
16501 S. Kedzie (Room 238)
Markham, IL 60426

Call: (708) 232-4150


Southwest Suburbs - Bridgeview (Until 8pm)
10220 S. 76th Ave. (Room 238)
Bridgeview, IL 60455

Call: (708) 974-6150


****Important Election Events for the 2012 General Election ---> Click Here****

Additional Information for the 2012 General Election Can Be Found at www.rockthevote.com