Does it have something to do with an election involving WJB or Woodrow Wilson?
Ratio of state income tax rate to state sales tax rates (red states have higher (top marginal) state income tax rate than sales tax rate, blue states the inverse)?
You're on the right track
Red states have a state income tax, blue states don't?
No, there are only 8 states without income tax (I'm pretty sure they are all blue on this map), but this includes income and other types of taxes in some way.
Direct vs indirect taxes?
