Constitution of the State of Illinois Art. III, § 1. Voting Qualifications

Every United States citizen who has attained the age of 18 or any other voting age required by the United States for voting in State elections and who has been a permanent resident of this State for at least 30 days next preceding any election shall have the right to vote at such election. The General Assembly by law may establish registration requirements and require permanent residence in an election district not to exceed thirty days prior to an election. The General Assembly by law may establish shorter residence requirements for voting for President and Vice-President of the United States.