Looked it up, yep, trains.I read online that the reason the time change happens at 2am is because back when they started doing it, the fewest number of trains were running at that hour.
Now that I'm retired, I'd vote to keep it the same, year round. I really, really like the late hours of daylight in the summer, though. If we stayed on standard time year round, I'm not sure if I'd get up at 4 am to take advantage of the light then.
We have discussed this before, maybe here or the old folks home. One suggestion is to split the difference and "spring forward" 1/2 hour and leave it alone.I like DST... If I had to pick one, that would be my preference. But the "fall back" is depressing.