It was 28 years ago today ...
I saw U2 on their 2nd (and first nationwide) US tour in March of 1981.
They had played Wolf & Rissmiller's Country Club in Reseda the night before, but I was living down in Newport Beach and didn't have a car, so I couldn't go.
The next night was in Anaheim which was a lot closer, so I was able to convince my roommate to drive his car. It was at a place called the "Woodstock Concert Theatre", of which I can remember little other than it being basically a dive bar/pool hall/Metal venue - complete with sawdust on the floor!
The gig was not very well-attended. Some lame inappropriate band named "Second Wind" opened. Guesses ranged from "a dozen" to "100 or so" - I'd guess somewhere in between, but to be honest I don't really remember the gig all that well so I don't remember how many people were there. Let's just say it didn't hold many people and there was a lot of empty room.
2 months later, KROQ had gotten a hold of "I Will Follow", U2 had extended the tour as a result and the band had come back to headline the 3,000+ capacity Santa Monica Civic (which I also attended). The rest is history. I'm glad I got to see them in the beginning.