After the shooting of Congresswoman Gabrielle Giffords in January of last year, urbanologist Richard Florida compiled several maps to plot the correlations between gun violence, gun laws, and other social indicators. They make for urgent reading after this latest mass-casualty shooting. In Florida's words:

The map above charts firearm deaths for the 50 states plus the District of Columbia. Note that these figures include accidental shootings, suicides, even acts of self-defense, as well as crimes. As of 2007, 10.2 out of every 100,000 people were killed by firearms across the United States, but that rate varies dramatically from state to state. In Hawaii, at the low end, it was 2.6 per 100,000; in New York and New Jersey it was 5.0 and 5.2 respectively. At the high end, 21.7 out of every 100,000 residents of the District of Columbia were killed by guns, 20.2 in Louisiana, 18.5 in Mississippi, and 17.8 in Alaska. Arizona ranked eighth nationally, with 15.1 deaths per 100,000.

With these data in hand, I decided to look at the factors associated with gun deaths at the state level. With the help of my colleague Charlotta Mellander, we charted the statistical correlations between firearm deaths and a variety of psychological, economic, social, and political characteristics of states. As usual, I point out that correlation does not imply causation, but simply points to associations between variables.

Some might think gun violence would be higher in states with higher levels of unemployment and higher levels of inequality. But, again, we found no evidence of any such association with either of these variables.

So what are the factors that are associated with firearm deaths at the state level?

Poverty is one. The correlation between death by gun and poverty at the state level is .59.

An economy dominated by working class jobs is another. Having a high percentage of working class jobs is closely associated with firearm deaths (.55).

And, not surprisingly, firearm-related deaths are positively correlated with the rates of high school students that carry weapons on school property (.54).

And what about gun control? As of July 29 of last year, Arizona became one of only three states that allows its citizens to carry concealed weapons without a permit. Might tighter gun control laws make a difference? Our analysis suggests that they do.

The map overlays the map of firearm deaths above with gun control restrictions by state. It highlights states which have one of three gun control restrictions in place - assault weapons' bans, trigger locks, or safe storage requirements.

Firearm deaths are significantly lower in states with stricter gun control legislation. Though the sample sizes are small, we find substantial negative correlations between firearm deaths and states that ban assault weapons (-.45), require trigger locks (-.42), and mandate safe storage requirements for guns (-.48).