Once upon a time it was illegal to have any fun on Sunday's. It was the day of prayer and reverence, and folks throughout America were required to abstain from leisurely activity. This even included a restriction on professional Baseball teams playing a game on that day.
How crazy is that, right?
It's hard to imagine a Sunday afternoon in the middle of summer without Baseball. They go hand in hand, and I dare say that if not for the melding of the two it would be that much harder to get up the next day for the start of the work week.