UA 1591 then AA 1253 at San Francisco
San Antonio → San Francisco → Chicago O'Hare
Timetable, San Francisco time
11:02UA 1591 from San Antonio at the gatealso NZ 2372, UA 2490, AC 4201, EK 6003
10:34AA 1253 to Chicago O'Hare leaves the gatealso IB 4495, QF 4697, PD 6338, GF 6456, EI 7303
23 h 32 apart on the timetable, overnight
AA 1253 leaves 23 h 32 after UA 1591 arrives on the timetable: more than half a day, so not a connection we count.