UA 1591 then B6 1734 at San Francisco
San Antonio → San Francisco → Boston
Timetable, San Francisco time
11:02UA 1591 from San Antonio at the gatealso NZ 2372, UA 2490, AC 4201, EK 6003
10:50B6 1734 to Boston leaves the gate
23 h 48 apart on the timetable, overnight
B6 1734 leaves 23 h 48 after UA 1591 arrives on the timetable: more than half a day, so not a connection we count.