Slavery's influence has been disproportionate to people of African descent in the U.S. The central tenet that they were taken against their will and forced to work. Many U.S firms made a lot of money off slave labor. Lincoln promised all the freed slaves 40 acres and a mule which they never got.
There are, of course, logical difficulties with this argument, most notably with the fact that there is not one living former slave in the U.S, that any civil claims would have expired under a statute of limitations, that many Americans born since the Civil Rights era and the end of the Civil War (plus immigrants) bear no responbility for any claims to damages, and, finally, that it's extremely difficult to quantify the damage done under any coherent tort system.
However, let's say that reparations are in order. I say that if you have a claim against any entity of "unjust enrichment" you cannot be part of that entity. African Americans suing the entire United States - Government, Society, Economy, Culture, and every institution - in some sort of "World Civil Court" for unique immediately identify themselves as a seperate party distinct from all of those mentioned in the suit.
If this is true, then the cohesion of the United States remains the same after reparations as it was before. This is because logically every African American who accepts any reparation for such an expansive crime as kidnapping from a native land and historical discrimination loses their claim to being part of the United States. America wouldn't be a land of people who had any claims against the culture, anyone who wasn't satisfied with the status quo because all those who weren't satisfied would not be a part of that society.
Here's my final reparations plan:
1) Give the reparations of whatever the African Americans ask for - which is something like $1.6 trillion -with the caveat that everyone who gets reparations MUST seperate from the United States within six months or reapply for citizenship in the U.S or any other country.
2) After twelve months of adjustment time, deport everyone who's left in the U.S and hasn't gained citizenship in another country to historic ports of departure for slaves in West Africa.