10 ILCS 5/5-50
Notwithstanding any other provision of this Code to the contrary, each election authority shall establish procedures for the registration of voters and for change of address during the period from the close of registration for an election until and including the day of the election. During this grace period, an unregistered qualified elector may register to vote, and a registered voter may submit a change of address form, in person in the office of the election authority, at a permanent polling place established under Section 19A-10, at any other early voting site beginning 15 days prior to the election, at a polling place on election day, or at a voter registration location specifically designated for this purpose by the election authority. Grace period registration and changes of address shall also be conducted for eligible residents in connection with voting at facilities under Section 19-12.2 of this Code. The election authority shall register that individual, or change a registered voter's address, in the same manner as otherwise provided by this Article for registration and change of address.
If a voter who registers or changes address during this grace period wishes to vote at the election or primary occurring during the grace period, he or she must do so by grace period voting. The election authority shall offer in-person grace period voting at his or her office, any permanent polling place established under Section 19A-10, and at any other early voting site beginning 15 days prior to the election, at a polling place on election day, where grace period registration is required by this Section; and may offer in-person grace period voting at additional hours and locations specifically designated for the purpose of grace period voting by the election authority. The election authority may allow grace period voting by mail only if the election authority has no ballots prepared at the authority's office. Grace period voting shall be in a manner substantially similar to voting under Article 19A.
Within one day after a voter casts a grace period ballot, or within one day after the ballot is received by the election authority if the election authority allows grace period voting by mail, the election authority shall transmit by electronic means pursuant to a process established by the State Board of Elections the voter's name, street address, e-mail address, and precinct, ward, township, and district numbers, as the case may be, to the State Board of Elections, which shall maintain those names and that information in an electronic format on its website, arranged by county and accessible to State and local political committees. The name of each person issued a grace period ballot shall also be placed on the appropriate precinct list of persons to whom vote by mail and early ballots have been issued, for use as provided in Sections 17-9 and 18-5.
A person who casts a grace period ballot shall not be permitted to revoke that ballot and vote another ballot with respect to that primary or election. Ballots cast by persons who register or change address during the grace period at a location other than their designated polling place on election day must be transmitted to and counted at the election authority's central ballot counting location and shall not be transmitted to and counted at precinct polling places. The grace period ballots determined to be valid shall be added to the vote totals for the precincts for which they were cast in the order in which the ballots were opened.
In counties with a population of less than 100,000 that do not have electronic poll books, the election authority may opt out of registration in the polling place if the election authority establishes grace period registration and voting at other sites on election day at the following sites: (i) the election authority's main office and (ii) a polling place in each municipality where 20% or more of the county's residents reside if the election authority's main office is not located in that municipality. The election authority may establish other grace period registration and voting sites on election day provided that the election authority has met the notice requirements of Section 19A-25 for permanent and temporary early voting sites.
10 ILCS 5/5-50