If you are using the Brevets app on your iPhone (sorry, no Android versions available at this time), then you should download the course named “RUSA-STL600K”.
The cuesheet for the course to be used in 2019 is located here:
2019-600kCueSheetWithMap updated on April 26, 2019. Update clarifies the course a little. New printed cue sheets will be available at sign-in.
I have also attempted to prepare the course for RideWithGPS although I am not sure it is correct. If you would like to look at it and compare it with the official cue sheet, it is listed on RWGPS as RUSA118-2019 Using US45.
Changes to the course were necessitated by the temporary closure of Highway 127 south of Alto Pass, Illinois.