Goggle Chicago scca. their autoX page normally pops up 1st.
http://scca-chicago.com/chicago-scca-solo/
Looks like they have an event this weekend 7-22.
Otherwise milwaukee region has one at miller park 7-29
http://scca-milwaukee.org/solo/solo-events/
You can also check out tri state sports car council as they do events in that area.
http://www.tsscc.org/event_schedule_rules.html