UA 3913 then UA 273 at Houston
Denver → Houston → Tampa
Timetable, Houston time
21:22UA 3913 from Denver at the gate
14:20UA 273 to Tampa leaves the gate
16 h 58 apart on the timetable, overnight
UA 273 leaves 16 h 58 after UA 3913 arrives on the timetable: more than half a day, so not a connection we count.