If you're interested, I'd probably start by looking at demographics at architecture schools to see who gets enrolled.
I suspect already that blacks are not proportionately represented... I think it would be pretty racist to imply that there are different career aspirations among different ethnic groups, so I think we just have to conclude that architecture programs systematically discriminate against African Americans.
Edit: I looked at Cornells demographics
here. Blacks are only 5.8% of the accepted class while they are over 10% or so in the general population. I just lost a lot of respect for Cornell. You would think they would not discriminate so flagrantly, but here we are. Racism is not dead in America. Absolutely disgusting.