Interesting map, for a few reasons. The United States is in green, which means there are “no special safety risks” to worry about. What I take this to mean is that as long as you stay out of, say, North Sacramento, or East Austin, when the sun goes down you’ll be safe.
The “pay attention, safety risks” label makes quite a big jump in my conceptual understanding of this map. What this warning means is that if you are particularly stupid, you won’t end up getting mugged and losing your wallet (like you would in green areas), you will instead end up losing your life or being kidnapped for ransom (or slavery).
This is quite a big jump, but it makes perfect sense, especially if you think about the jump in terms of inequality and, more abstractly, freedom.