What large cities can you mention that have at least 80% whites?
With 5.5% black, and 3% Asian leaving 91.5 % for white and others, I would say Scranton, PA. It comes in comes in with 84.1% white under the modern classification. Under the old classification, it would have been the 91.5%. That's when we only had three racial classifications - Caucasian, Mongoliod, and Negro. Polynesians and American Indians would fall to the Caucasoid group.
Of cities 200,000 or greater, there are only three:
Spokane, WA - 86.7%
Scottsdale, AZ - 83.7%
Lincoln, NE - 83.1%
Of cities 500,000 or greater, the highest is Portland, OR: 72.2%
Portland has serious problems with black violence and even Spokane had one knockout incident on an elderly man back in 2013. There’s also a video of a brawl among some black women on a bus in Lincoln back in 2011. That said, the problem is in pretty much any large place.