During the late 80's and early 90's (the crack-wars crime wave) blacks were killing almost 50% of all white victims and about 91% of all black victims (the black-on-black crime rate is about the same today, hasn't changed by more than a percentage point or two).
DoJ crime stats were quoted in Scientific American in an article on "stranger murder" that appeared about 1994. The DoJ stats attributed 25% of non-black victims' murders to persons of "unknown" racial affinity -- which was a euphemism for "unidentified blacks", by comparison with adjacent violent-crime rates of a similar nature (armed robbery, aggravated assault, etc.). Rape patterns were slightly different, but blacks still showed a pattern of out-group predation.
For several years, young black men supplied something like 75% of all murderers, and more than half of all rapists.
Abraham Lincoln foresaw this disharmony and unhappiness; hence his interest in the colonization movement until the last day of his life. When he died, he had Gen. Daniel Sickles (of the Wheat Field at Gettysburg) in Panama, exploring the possibilities of building a canal there.
Lincoln wanted to use emancipated slaves, about 2,000,000 in all, to build the Panama Canal -- and then leave them there when the canal had been completed. That would have been somewhat less than half of all the slaves then living. He was doubtful of the proposition that whites and emancipated blacks could co-exist. Neither were the Radicals who inherited Reconstruction; which was why they insisted that ex-slaves remain in the South and not be allowed to migrate to the North.
That might have been the case. And what did white's do? They obviously went to the suburbs. They left the inner cities.
I remember reading something Sherman once said, basically 'he' had to kill two hundred thousand or so rebs, for their own good, to save them.
Things come in cycles, at the turn of the 20th century, America was being divided with immigrant crimes. Unfortunately, the Gov't has divided so many people that things will fall apart when the goal is to bring everyone down.