One of the interesting aspects of my research on John Bingham (for the biography that I am writing about him) was his relationship with Titus Basfield, an ex-slave who was his college classmate and lifelong friend. There is a suggestion in one of Bingham's letters that he wrote the Equal Protection Clause with Basfield in mind, though I have not yet verified this claim. What is clear, though, is that Basfield is probably the most significant example of undergraduate affirmative action in our history.
Basfield was a slave whose freedom was purchased by abolitionists in the early 1830s. (There is an urban myth that his mother was owned by Andrew Jackson, and I'm trying to run that down.) He moved to Ohio and came to the attention of the Reverend John Walker, a supporter of African-American equality who was the founder and leader of Franklin College. Walker personally recruited Basfield to the college and gave him a room rent-free so that he could pursue his studies. In exchange, Basfield did odd jobs at the school and served as the sexton in Walker's church. When Basfield graduated in 1837, he was the first African-American to receive a bachelor's degree in Ohio, and went on to become a successful minister.
Why is this story important? Partly because one of Basfield's ten classmates was John Bingham. I was at a museum dedicated to Franklin College--the school no longer exists--and saw a picture of Franklin in the years when Bingham and Basfield attended. It was basically just a private house. In other words, John Bingham spent every day of his formative years with a free black man who was treated as his social equal. This was an extraordinary experience at that time, and (as their friendship and correspondence until the 1870s suggests), it left a deep impression on both men. My other observation is that Basfield was a textbook example of racial outreach (and financial aid) by a university to make the student body more diverse. (To use modern parlance, you could say that one African-American in a class of 11 was a "critical mass."). More important, that diversity appears to have had a profound effect on the thinking of one of our most consequential constitutional figures.
Does this mean that John Bingham saw affirmative action as consistent with the Fourteenth Amendment or diversity in higher education as a compelling state interest? Not necessarily. Franklin College was, after all, a private institution, and one might think that a state institution should be treated differently. Nevertheless, I think this history offers some support for the Court's holding in Grutter.