According to the New York Times, my great home state of New Jersey loses more residents to out of state colleges than any other. Being a resident, I can tell you that New Jersey offers the worse in-state tuition discounts on the planet, also New Jersey is really two states: The New York influenced North and the Philadelphia influenced South. So where does your state stack up? Check the article. (if registration is needed, enter in “biteback” for user and pass.)
If you decide to stay in one of the states with terrible discounts, be sure to take advantage of all the scholarships you can!