City of O'Fallon issued the following announcement on Nov. 26.
Notice is hereby given, that the Office of Jerry Mouser, Local Election Official in and for the City of O’Fallon at 255 S. Lincoln, O’fallon, Illinois, will be open from 8:00 a.m. to 5:00 p.m. beginning Monday, December 10, 2018 through Monday, December 17, 2018 for the purpose of accepting candidate petitions for the consolidated election to be held April 2, 2019 for the Office of Alderman.
Original source can be found here.