I don't know if my anecdote constitutes data, but the first time I went to the US in 1999 I landed at JFK, hired a car, was driving along slowly looking for an entrance to a freeway to Brooklyn. A guy in a convertible pulled out in front of me so close that I had to swerve into the left lane to avoid him, once I passed him I changed back into the right lane so I could use the upcoming freeway entrance, the guy roared past me, swerved back in front of me and jammed his brakes so quickly I barely was able to stop without hitting him. He then sat there in front of me yelling something for about 30 seconds whilst waving a gun in the air. He then took off and I never saw him again.

I'm not sure what that means exactly but I think it indicates a culture of aggression, bullying, anger, self importance, and when coupled with loose gun laws it means lots of guns get fired.