After the convention, there was some discussion about the River Queen, Holiday Queen, and Holiday Casino.

FWIW, we went to the flea market in St. Charles, Illinois today. We bought a matchbook cover from the River Queen Casino "on the strip". It didn't have an address, but it did have a phone number. The phone number matches the listing for the Holiday Casino, in the 1973 phone book. (There's no listing for the River Queen Casino or the Holiday Queen Casino.)