On the whole, US cities become terrible all too quickly. Many downtown areas mostly empty out around 5-5:30pm, and then what?

Come to think of it, cities in the Western Hemisphere in general are no great shakes for ambling. The only time I should have felt unsafe was in Santa Ana, El Salvador; two cops stopped me in my tracks, and took me back to my hotel. They said that wherever I was wandering was full of gangs.

That's just one aspect of "feeling unsafe," but in reality, I'll walk anywhere at anytime of the day.