==RE 20,000 undergraduate students== 

 anyone familiar with elite colleges, will know few schools have such a large populous at that level. in fact, few ivy league etc have such a large number of students with most of these universities having a more pronounced number of graduate students, respective to the number of undergraduates.  there is NO way that Columbia had that many "undergrads" at that time. 

 Columbia University currently has less than 8,000 undergrads at this time. it would be interesting to know how many were at the university in the 80s.  furthermore, undergrad classes are selected for major areas and disciplines and progression (senior, junior...).  the representative number of peers for Root would be a much smaller number and the "20,000" claim is specious and fraught with subverting interest that Root would have been a prospective peer to Obama.