A new study ranks Arkansas seventh-highest in road fatality rates, with 16.3 per 100,000 population. More rural states tend to do the worst. Montana led the list. The lowest rate was in the District of Columbia, a wholly urban area where, for one thing, speeds aren’t as high on average.

Here are some other correlations the Michigan researchers found. Positive indicators for higher fatality rates were:

* Higher speed limits.

* Miles driven.

* High poverty and lower income. (older, less reliable cars, maybe?)

* Less education.

* Voting Republican. Really.

Car deaths also track political ideology. They are higher in conservative states and lower in liberal ones. Car deaths are positively correlated to the share of voters who voted for the Republican candidate Mitt Romney in the last presidential election (.66), and negatively correlated to the share who voted for Obama (-.66). Of course, more conservative states are often the more sprawling and car-oriented ones, while liberal ones are denser and more transit-oriented.