UA 3913 then AC 592 at Houston
Denver → Houston → Toronto
Timetable, Houston time
21:22UA 3913 from Denver at the gate
11:55AC 592 to Toronto leaves the gate
14 h 33 apart on the timetable, overnight
AC 592 leaves 14 h 33 after UA 3913 arrives on the timetable: more than half a day, so not a connection we count.