<p>Not everyone necessarily applies to the same list of schools, just because they are similar in “prestige”. Of course, Harvard might get more applicants applying “to see what happens”, but it could also very well be that Harvard seems a more obvious reach on more college lists. Say, people who want to study in Boston (thus apply to BC, BU, Tufts, idk) , people who like urban-ish schools (might opt for Chicago/Penn/Columbia as well etc.), people who find financial aid really important , people who want a strong economics program, etc all apply to Harvard. </p>
<p>People who want a more suburban environment, small town feel and undergraduate attention, might apply to a range of LACs and similar research universities and pick Princeton as their reach. </p>
<p>It could very well be that Harvard (although Princeton and Harvard share a lot of (these) characteristics -hence the high number of cross applicants) attracts more applicants from their particular nichegroup than Princeton does from its particular niches, because Harvard’s specific characteristics apply to more different types of students. </p>
<p>It can be compared to Columbia and Penn: Both are considered somewhat equal in academic respect, and have a lot of cross applicants, but Columbia receives more applications because a lot of people are really attracted to New York City, thus also becomes on of the top choices of all the people who apply to NYU, Barnard, etc. Penn attracts a lot of people who, for example, want to go into business. Possibly the group of high school seniors who want to go into business (and apply to top schools) is smaller than the group of students who desperately want to live in NYC in absolute numbers. </p>
<p>Furthermore, people are put off by really low admit rates. The lower the percentage of admitted students gets, the more people decide to try their luck somewhere else. With fewer spots, the single digits are reached faster, thus fewer people apply. The number of spots obviously does count. </p>
<p>This was a rather long post.</p>