I thought this was illegal everywhere. I would look up you department of labor for your state, or workforce commission. I can answer this question regarding Texas where I live, but not Illinois. Take a look at the following. https://www.illinois.gov/idol/FAQs/Pages/minimum-wage-overtime-faq.aspx or http://www.ilga.gov/commission/jcar/admincode/056/05600210sections.html

I think most jobs are required to be paid that for overtime. Maybe look it up though - make sure you're a non-exempt employee.