In this scenario, a genie takes a wish from an oddball (black separatist, racist non-black person, who knows) and now there's a separate version of the country with only the black population.
Alternatively, the centers of population magically change in the existing US to correlate to where black people live.
This is a theoretical setup that I thought would be fun thought experiment. Alaska and Hawaii have been reverted to territories. Both Dakotas, Wyoming, Montana, and Idaho have suffered the same fate although there are some calls to annex the 5 former states into Nebraska to create the state of "Lincoln" or "King". (which I assume wouldn't have more than the at large CD)
Upper New England reverted into territories for a time until they all agreed to merge into Massachusetts to create the state of New England. Utah has rejected becoming a territory or part of "Lincoln" and has ended up merged into Colorado, and New Mexico followed suit and has been annexed by Arizona.
Washington DC has been admitted as the nation's 41st, not 51st, state. There are 82 senators.
US states with number of CDs:
Electoral version: