http://www.nationalatlas.gov/articles/people/IMAGES/crime_mu...
What the heck is wrong with Northern Idaho? Elko Nevada? So Cal's inland empire? I didn't think there was anyone to kill in western New Mexico. The Mississippi Delta also doesn't look like a healthy place to live.
If we excluded Louisiana, the murder rate would probably plummet to mostly normal levels. And it just isn't New Orleans.
Notice that the many of the places with the lowest murder rates also tend to be sparsely populated. What you're seeing is the increased variance that one should expect to see when dealing with smaller sample sizes, not evidence that small towns are more dangerous than big cities.
http://www.textmap.com/offence/vehicular-homicide.htm
I bet we would see more geographic correlation with not too much variation in city areas (e.g., the Delta is still a dangerous place to live, which would correspond to anecdotal evidence). Unfortunately, I can't google up a decent gun homicide heat map.