We don't have many earthquake tremors in Chicago but the New Madrid fault has been acting up lately.
I felt it today with no external factors (rain,etc.) involved. One of the last one's epicenters was Joliet at 3.5 mag. (?) about 10 miles away.
There have been several tremors lately on the MO-AK-Ohio river fault line. The last major quake on this fault line was 1818 and it was devastating.