10 ILCS 5/4-17
Following the general election in November, 1946, and following the November election every 4 years thereafter, the county clerk shall examine the registration record cards, and shall send to every voter who has not voted during the preceding four years a notice through the mails, substantially as follows:
Notice of suspension of registration:
"You are hereby notified that your registration will be cancelled according to law for failure to vote during the last 4 years, unless you apply for reinstatement within 30 days. You may reinstate your registration by signing the statement below and returning it to this office or by making application in person to do so."
Application for reinstatement of registration:
"I do hereby certify that I still reside at the address from which I am registered and apply for reinstatement of my registration.
Signed ....
Present Address ....
Date ...."
In case the elector is unable to sign his name, the application for reinstatement shall be made at the office of the county clerk, or in the case of an elector, absent from the county of his residence, it shall be made before the clerk of a circuit court in the county in which the elector is temporarily detained.
After the expiration of 30 days the county clerk shall cancel the registration of all electors thus notified who have not applied for reinstatement.
A proper entry shall be made on the registration record cards for all electors whose registrations are reinstated. Any elector whose registration has been cancelled for failure to vote may register again by making the application therefor in the manner provided by this Article 4. When a registration is cancelled or erased under this or other sections of this Article 4, a proper entry shall be made on the original and duplicate registration cards by the county clerk, which shall then be placed in a file of cancelled registrations and shall be preserved for 2 years from date of cancellation. The county clerk shall, however, place the cancelled cards in a suspense file, and reinstate them at any time within such 2 year suspense period, when a person's registration is cancelled under this or other sections of this Article for failure to apply for reinstatement or to appear in proper time, and there is sufficient subsequent showing that he is a duly qualified elector.
10 ILCS 5/4-17