The Topeka and St. Louis events have opened registration on MSR
Topeka: https://www.motorsportreg.com/events/ks-kcr-scca-solo-midiv-presented-by-r-s-sps-heartland-motorsports-park-kansas-967372
St. Louis: https://www.motorsportreg.com/events/midwest-divisional-solo-series-events-7-8-family-arena-scca-st-louis-055591