My niece's kids will be starting Aug 4th or something like that. That school district is going to year-round schooling, so they'll be having 2 weeks off every so often.
Some of Chicago's schools (the early start schools - year round schooling) will also be starting at the beginning of August and the rest of Chicago's schools (traditional school year)will be starting after Labor Day.
My nephew starts Aug 17th and the schools in Barrington (where I work) start Aug 23. Every district in Illinois has a different start and end time - it all depends on where you live.