You can have "Veteran" printed on your Illinois driver’s license or state ID card, which works as proof of eligibility for other services and benefits. Adding it outside your renewal period costs $5 for a license and $10 for an ID card. There is no charge if you are 65 or older.
Take your proof of service to an Illinois Secretary of State office and ask for the veteran designation.
One of the following: your DD214, a Certification of Military Service on NA Form 13038, a DD2 retired ID card, a VA ID card, a VA Summary of Benefits letter, or another official Department of Defense document showing you were honorably discharged.