Well, the term "road rage" was coined about DFW drivers by the insurance companies and the car insurance is among the highest in the country.
Using a vehicle as a threat of violence or actually carrying that out was the highest in Dallas of all the cities in America. Spokesperson for Allstate in Austin remarked that it was so much higher that it was alarming as to what could be causing this to escalate.
I have been shown a gun by the driver of a vehicle twice in my life, both in Dallas. Once on the NTT and once on Central Expressway. I could get quite pissed myself in traffic and a guy cut me off and made me slam on my brakes and I gave him the one finger wave. I didn't think anything about that until about 10 minutes later, he pulls up on the passenger side with his window down, shows me what looked like a Dirty Harry gun, smiled and rolled the window back up. That was the last time I ever flipped anyone off in a vehicle.
When I go to Dallas these days I can feel myself tightening as I approach on I-35 because of the aggressive driving and that was the major complaint I would hear from OK people when I commuted from there weekly. I cannot explain why Dallas is like that because I've never driven in any city that has that issue as bad as they do. They give defensive driving a new twist because it's not just the vehicle you have to be on guard about but what's driving it.