10 ILCS 5/6-49
The registration hereinabove provided preceding the first Tuesday after the first Monday in November, 1936, shall constitute a permanent registration, subject to revision and alteration in the manner hereinafter provided. However, except as provided in Section 6--49.1 of this Article, the registration hereinabove provided for shall constitute a permanent registration only until September 15, 1961, in municipalities having 3 days of precinct registration preceding the 1962 primary election and only until the last day of precinct re-registration in 1970 in other municipalities, at which time such registrations shall become null and void and shall be cancelled immediately thereafter by such Board.
All registrations subsequent to that hereinbefore provided shall be upon registration record cards provided by the Board of Election Commissioners in accordance with the provisions of Section 6--35 of this Article.
10 ILCS 5/6-49