For many years, commencement was held on the opposite side of Lovett Hall from where it is today. It was also held in the evening. (You can see here the shadow of the building as it lengthens across the crowd in this picture from 1982.) This was, I’m fairly sure, an attempt to deal with the constant problem of the Houston heat in May.
Typically, it was getting pretty dark by the time things were well underway, as you can see here:
But in 1986, commencement moved to the main quad and the time was changed to the early morning.
Why? Well, as with most things, there isn’t a memo anywhere that says “We moved commencement because . . . .” Personally, I would have moved it for aesthetic reasons alone–there’s a street stuck right in the middle of the thing that’s not really very attractive. There is a good bit of evidence, though, that the real concerns were about decorum (or the lack thereof). I’m not sure if that’s all there was to it, but I can certainly testify that the switch did lead to different beverage choices.