We live in NY and decided to get the kids non-drivers license ID's for the kids (age 6 & 8). We just went down to DMV filled out the paperwork had the pictures taken and paid about $8.00 per ID. They'll come in the mail in a couple of weeks. They're good for 5 years. You may want to see if Illinois offers something like that.
We're flying Southwest and we didn't need ID for the kids in April, but with all that's going on (we're WDW bound again in November), we decided to get the ID's as a safety precaution.....