The first question one asks is "what’s “diversity”? Is it considered to be “diverse”, if it includes the top kids by income from across the USA and the world, who all went to a handful of expensive elementary schools, all went to the same handful of expensive private high schools, whose parents have the same narrow set of occupations - law, business, and politics. The fact that their country of origin and even ethnicity may differ is dwarfed by the commonalities of a wealthy and privileged childhood.
Time and again, the income diversity in the most expensive and popular colleges has been demonstrated to be extremely low, so the claim that they are diverse because their 26 students accepted from an exclusive private boarding school for the wealthy are super wealthy kids of Chinese, Indian, and White American origins is simply “gaming” the system. Those kids are more similar to each other than any of them is to a poor person of the same racial/ethnic origin.
@TheGreyKing Large public colleges in mostly White states are going to be mostly White, so the public universities of New Hampshire, Vermont, Maine, or West Virginia are going to be less diverse the public universities in, say, New York, New Mexico, or California. As for geographic diversity, the entire point of public universities is to serve the people of THAT STATE. The University of ILLINOIS was established primarily to serve the people of ILLINOIS, not the people of New York, Connecticut, or the UK. Same for the University of Indiana, the Ohio State University, and Texas Tech. The fact that between states defunding their universities and universities preferring OOS dollars to serving the people of their state (I’m looking at YOU California and the UCs!!) this is not the case for some public universities does not change this fact.
High geographic diversity is many public universities is an indication of the failure of the public university system, not an indication of of anything truly positive.
Offhand, I could think of a dozen ways in which a college experience at SDSU would be BETTER to that at Harvard.