Compare the Gini coefficients for the various states. (Remember that lower is more equal.) There are individual oddities that one could fairly point out that make a state look better or worse than it might deserve. But there is a solid and easily-observable tendency that blue states are more unequal in income, red states more equal. Notice also that the increments are small until the last three: Connecticut, New York, Washington DC. As the high school social studies texts might ask, "What do you think is happening in those states?"
Alert readers might pick up another trend, but even noticing it will not answer fully the questions: "Why do poor people do so badly in blue states? Do they start off worse? Do they get poorer when they are there?"