It's not a surprise, if people can conceal a handgun, you're far less likely to violently attack someone if there's a potential your victim or a bystander ends you.

https://en.wikipedia.org/wiki/Constitutional_carry

It's called constitutional carry, gun freedoms in the usa greatly increased since ~2015 state by state. No permit required to conceal carry a handgun. The USA is rapidly switching states over without any hassle because of the immediate significant drop in violent crime.

https://en.wikipedia.org/wiki/Gun_laws_in_the_United_States_...

Essentially a few states have had public data on violent crime for decades and the year they implemented constitutional carry on average they have a ~10% drop in violent crime.

What's very telling as well. Places like michigan, illinois, new york, california. They are holdouts on this gun freedom and they have been rewarded with having the highest violent crime cities.