I went to IPEDS and downloaded all enrollment at post-secondary institutions in the US that receive Title IV funds.
This is Fall 2017 data: Some context:
Let's get rid of for-profits. That leaves us with 16,219,487 in 3,822.
Let's also only look at four-years: We're now at 9,532,180 in 2,714.
Let's say the smallest 825 four-year private colleges all closed at once. What percentage of students at four-year privates attend THESE 825 four-year privates?
Guess.
Download your own data if you want to get fancy.
Now, guess.
Against the larger backdrop, it's .77% (about three-quarters of one percent) of all the 17.9 M undergraduates.
And, yes, colleges closing can be devastating for faculty, employees, students, and even cities. I know that.