10 ILCS 5/5-1

Except as hereinafter provided, it shall be unlawful for any person residing in a county containing a population of 500,000 or more, to vote at any election, unless such person is at the time of such election a registered voter under the requirements of this Article 5 or is exempt under Section 5-29.01 from registration. Provided, that this Article 5 shall not apply to electors residing in cities, villages, and incorporated towns in this State which have adopted or are operating under Article 6, 14 and 18 of this Act, or to electors voting pursuant to Article 20 of this Act.