Gun ownership does not cause an increase in violence. If violence increases it shows a need for gun ownership for self-defense, but not by whim. The use of force to protect the rights of the individual must be under objective control, delegated but not surrendered to government. When violence increases it means a failure of government to perform its primary function. A propensity for increase in violence may be due to a surge in criminal activity or it may be due to a more general breakdown in civilized behavior. Either way, self defense is a moral requirement. But the last thing we need is more people running around in a fad to shoot it up in the name of self defense.

I suspect the correlation would be even more stark if you looked at urban/rural vs. voting vs. respect for gun rights. States with large urban populations went strongly for Clinton and are more restrictive of gun rights. In urban environments, neighbors and police are closer, so people feel less need for a gun. (Note: I'm not validating the "what do you need that gun for" argument, but just speculating on people's motivations.)

If we could somehow makes the rules customized by city or neighborhood, the whole debate would be moot. Most of the country by area would recognize gun rights.

Horizontal axis changes scale on last chart.

The charts definitely DO need some explanation. Otherwise we are no better off than the people who decry that half the children are below average.