Why were college towns so Republican before the 70's?

[Skill and Chance]

As others have pointed out, pre-1960 college graduates were a very economically elite set.  And private school professors circa 1915 were likely to hail from top 0.1% graduate degree and trust fund backgrounds which were obviously very Republican back then.  It's important not to overstate this, though. There was probably a meaningful 25-30% Democratic minority among the very most educated 100 years ago.  Even William Jennings Bryan had a graduate degree.       

[Del Tachi]

Yeah, saying that most of the difference is because of the voting age being lowed to 18 is stupid answer.

18-to-21 year olds vote at such abysmal rates that I doubt it would have made much of an impact, and most college students are either ineligible/don't bother registering to vote in the towns in which they go to college.