East St. Louis, Gary, and Camden seem to be the leading the pack. Having been to all three, I would give the nod to ESL over the others. Gary and Camden seem to have a bit more life in them and each are close to cities (Chicago, Philly) that, while having their own problems, are at least worthy of a visit.
East St. Louis, on the other hand, looks as if it were hit by the zombie apocalypse - huge swaths of empty land, broken up by a few burnt-out buildings. I'm surprised even 25,000 people live there. Plus, real St. Louis is almost as bad. Its population dropped from 800,000 to 300,000 over the past 60 years or so, even though its city limits stayed the same. Truly amazing.
I figured there would be more people listing Detroit.
I've spent some time in Reading, PA. Not up to the Big 3, but pretty rough. Deceptive because it looks so pretty from a distance.
Colorado Springs? Boston? Columbus? Worcester? Omaha? Is this trolling or have the people listing them not traveled anywhere?
Someone mentioned Chesapeake, VA. I grew up in Chesapeake. It's a boring suburb, really more like a county than a city, with its own little "towns" scattered about, not much to do, relatively low crime, nothing special but hardly the worst place in America. Boring is not the same as worst.