There are historical reasons, e.g. racism embodied in the 3&#x2F;5ths clause of the US Constitution. There&#x27;s American mythology that racism is principally a southern flaw even though there were no Major League Baseball teams in the south when Jackie Robinson broke the color barrier...unless one considers  Washington D.C. a southern city and it is and was directly under the control of Congress in which since the US Civil War legislators from southern states have been in a distinct minority.<p>But even with free choice, it is worth considering the effects of Schelling&#x27;s segregation model. Across a large population small preferences go a long way.<p><a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Thomas_Schelling" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Thomas_Schelling</a><p><a href="http:&#x2F;&#x2F;www2.econ.iastate.edu&#x2F;tesfatsi&#x2F;demos&#x2F;schelling&#x2F;schellhp.htm" rel="nofollow">http:&#x2F;&#x2F;www2.econ.iastate.edu&#x2F;tesfatsi&#x2F;demos&#x2F;schelling&#x2F;schell...</a>