New York state is the lowest usage per capita, 297.0. (DC isn't a state, but uses only 214.4 gallons per capita per year.)
Oklahoma is the worst, at 625.8. I think they have really low diesel taxes, so truckers tank up in OK, which may distort the data.
It makes sense that low-density, rural states would use more gas. High density areas mean that public transit is easier to implement and you don't have to drive as far when you want to.
As it turns out, the correlation between gas use and density is only 0.114, which isn't significantly different from zero (p=0.1162), and a regression doesn't have a significant slope (slope=-0.1585, p=0.116). On the other hand, a non-parametric correlation is significant (rho=-0.343, p=0.01516), so take that all with a grain of salt.
There's no lesson there, just something to ponder.