That would be since 1990 and the honest answer would have to be
That is, unless you count the New Black Panther party guys with clubs in Philadelphia election precincts. You know, the ones Eric Holder refused to prosecute because they were his people.
Bill Clinton while governor of Arkansas was sued for voter disenfranchisement.
He didn’t like the way blacks voted so he just overturned the election.
That was sometime in the mid to late 1980s which is why they are only going back 1990 so Bill Clintons history of racism isn’t hauled out for everyone to see.
BTW Clinton was also sued for racial profiling about the same time. He didn’t like those with brown skins driving through his state without his permission.