The most diverse city in the US is San Jose, which is followed by the center of the world, NYC. As for the most diverse zip codes in the land, South Seattle finds itself not in the top position but the seventh one, which isn't bad at all. The Atlantic Cities:

Also, some of the most diverse neighborhoods in America are located in metro areas that aren’t especially diverse overall, like Seattle (67 percent white) and Boston (69 percent white).
If you live in Seattle, and want to live in the future, the future which is represented by the current president, then you have to live where I live. And I live where this bus is going...