I would have to take issue with blt's contention that "probably, the worst case scenario as far as the USA is concerned would be to be a young Black, Latino, or Native man or woman walking in an upperclass, white neighborhood."
The worst thing that would happen would be they would find themselves stopped by a patrol car and questioned.

Having said that, I have walked alone through parts of Miami at 3am.where no white American would dream of venturing and never experienced a problem. Maybe, as Larry said, it helps to be redhaired and Celtic. (Being six foot tall might help as well) I believe it is even more important not to have a victim mentality.

Murray