UA 5756 then DL 1371 at Detroit
Chicago O'Hare → Detroit → St Louis
Timetable, Detroit time
13:28UA 5756 from Chicago O'Hare at the gate
12:40DL 1371 to St Louis leaves the gate
23 h 12 apart on the timetable, overnight
DL 1371 leaves 23 h 12 after UA 5756 arrives on the timetable: more than half a day, so not a connection we count.