DL 1007 then UA 1254 at Atlanta
Washington National → Atlanta → Denver
Timetable, Atlanta time
21:41DL 1007 from Washington National at the gate
11:14UA 1254 to Denver leaves the gate
13 h 33 apart on the timetable, overnight
UA 1254 leaves 13 h 33 after DL 1007 arrives on the timetable: more than half a day, so not a connection we count.