The area around Harvard Square is livelier than Dinkytown or Stadium Village, even though the University of Minnesota Twin Cities, with some 52000 students is 2.5 times larger than Harvard with just over 21000 students.
In part this is due to concentration, the U splits its adjoining retail into Dinkytown and Stadium Village plus West Bank and St Paul. Still, the collective activity around the H outweighs that around the U.
Are there other factors which might explain this:
Block size: blocks are much smaller in Cambridge, and even the alleys are named and have fronting activity. I am not sure if this is a key or merely coincidence, but it creates more perimeter and thus more street fronting surface area, and thus more shop sites per unit area. The middle of blocks in Dinkytown are generally parking not shops, Dinkydale excluded.
Accessibility: Boston’s T transit system drops hoards off at the heart of the square. I took transit from the airport here, the Silver Line BRT to the Red Line subway. It was relatively painless, though someone should resurface the road in the Ted Williams Tunnel.
Navigability. I think this is an important point, there seem to be more people here because they are lost and wandering around. The streets go hither and yon, and though the area is not large, it is not well organized. Streets curve reducing the ability to use landmarks.
Width: The streets are also narrower, so it feels easy to just cross the street. Several blocks are pedestrian only, and elsewhere the pedestrian is in charge.
Branding: Going to Harvard is so much more than the education, it is the adoption of a brand. Several stories of the Harvard Coop, the “bookstore” are devoted to Harvard gear, more than even the U of M bookstore. Harvard is the most elite of educational brands, and this help attract tourists who want to bask in its rays. The book part of the bookstore is however in the neighborhood, and a major anchor there, rather than inside the student center.
Tourism: The history and the activity of Cambridge attract tourists. The tourists bring more activity. Positive feedback in action. The U cannot easily manufacture a history, though I am sure people are working on it, after all, isn’t that what the stadium is for. It is just a bit too far from the Mill District or St Anthony Main to make those genuinely historical areas contiguous, i.e. to have a thread of connective activity tissue linking them.
Income. The average household income in Cambridge ($69,227) is higher than in Minneapolis ($45,538). Hence with more money sloshing about, there is more out-of-home consumption, thus demand for more out-of-home restaurants and shops.
Harvard has lots of other attributes: The House system, Bricks in sidewalk, Bike lanes, and One way streets, but I don’t think those are determinative.