superstar88, welcome to FlyerTalk. In long-past days when United had maintenance bases in both SFO and, 10 miles across the Bay at OAK, it had scheduled, mainline service between the two cities, or at least, one-way between SFO and OAK. Took several of those 10-mile trips. That may be the record, or close to it, for the shortest distance for scheduled jet, mainline service.