That's more the 100 years after the Reconstruction Amendments. [2] Racism is the weft upon which much of US history has been woven.
[1]: https://en.wikipedia.org/wiki/Swann_v._Charlotte-Mecklenburg...
[2]: https://en.wikipedia.org/wiki/Reconstruction_Amendments
http://www.nber.org/digest/may11/w16664.html
>Rucker estimates that each additional year of exposure to desegregated schools increased black mens annual earnings by roughly 5 percent, increased their wages by 2.9 percent, and led to an annual work effort that was 39 hours higher. At the same time, for these black male adults the probability of poverty decreased by between 1.6 and 1.9 percentage points. Overall, five years spent in desegregated schools yielded an estimated 25 percent increase in annual earnings and increased annual work effort of 195 hours. Desegregation also resulted in significant long-run improvements in blacks' adult health, as measured by self-assessed general health status; the effect of a five-year exposure to school desegregation is equivalent to being seven years younger.
Some of the first American gangs were Irish (Forty Thieves, Dead Rabbits) and integration of the Irish in American society certainly didn't cause an increase in Irish street gangs.
C.f. http://www.amazon.com/World-We-Created-Hamilton-High/dp/0674...
> Rucker estimates that each additional year of exposure to desegregated schools increased black mens annual earnings by roughly 5 percent, increased their wages by 2.9 percent, and led to an annual work effort that was 39 hours higher.
Also, what exactly does that mean? E.g. a person going from an all black school to a school that's 90% white is going to have almost nothing in common with someone going from an all black school to a school that's still 90% black. I skimmed over the study, but I'm having trouble understanding how they are controlling for demographics and what they call the 'black-white exposure index'.
It's not entirely accurate to say it was an unintended consequence. The Coleman Report predicted these sorts of issues if desegregation was implemented in the way that it was.
> And how is this connected to gangs?
C.f. the book I linked to.