Under which condition is someone eligible to vote in Illinois?

In Illinois, eligibility to vote is primarily determined by age among other requirements. To be eligible, an individual must be at least 18 years old on or before Election Day. This age requirement is established to ensure that voters are mature and responsible enough to engage in the electoral process. While there are additional criteria, such as being a citizen and a resident of the election district, the age requirement of 18 is a fundamental condition that clearly defines who can participate in elections.