New York State has done a great list of turntable/roundhouse locations on their forum.
Let's see how many midwest ones we can find, existing or previous.
Using
https://mapper.acme.com/" onclick="window.open(this.href);return false; list and locate the ones you are aware of by posting the Lat Lon such as:
N 39.85897 W 88.16217 which was the C & EI Villa Grove roundhouse and turntable.
N 41.95376 W 87.93180 CMSP&P Bensenville, IL
N 40.74983 W 88.40503 WAB Forrest, IL
N 40.36476 W 87.65043 C&EI Rossville, IL
N 38.63346 W 90.15194 B&O Granite City, IL
N 41.83767 W 87.76564 CB&Q Cicero, IL
N 38.50103 W 89.14528 ICRR Centralia, IL
N 41.69786 W 87.56815 C&WI? or NYC&STL? South Deering (Chicago) IL
N 41.66790 W 87.67300 CRI&P Blue Island, IL
N 38.50101 W 89.14530 ICRR Centralia, IL
N 41.51597 W 90.41635 CRI&P Sylvis, IL
N 39.53718 W 89.30551 C&IM Taylorville, IL