That was the curse of Barack Hussein Obama. Tens of millions of well-meaning white voters decided that electing a black man to lead the free world would be a HUGE boon to race relations within America... but sadly, the exact opposite was the result (as with almost every well-meaning Left-wing idea). Race relations took an immediate nosedive, according to every single poll on the matter. Whereas nearly 80% believed race relations were good in the US in 2007, the number collapsed down to barely 50% by the time Obama left office.
It might have been achieved, had a different "black" politician been elected, but Obama was not that. He was a puppet, a hologram, seemingly of unseen powers who facilitated his rise and seemed to place him in his position while gaslighting the American public at the same time
Obama purposely chaos in whatever he touched - from Libya, Syria and Ukraine, to the streets of Ferguson, Oakland and Minneapolis to American health-care system, to the political corruption of all of Federal Government in DC.