For students in the Western United States, there is also the Western Undergraduate Exchange.
http://www.wiche.edu/wue
It allows out of state students from western states to apply for 150% of in-state tuition at participating public universities. Most public universities in the west participate,
New Mexico/Colorado/S. Dakota/N. Dakota are the eastern most states and Hawaii/Alaska are included too!
Keep in mind, it isn't automatic, nor is it a guarantee. Many schools have SAT/ACT + GPA requirements for eligibility AND limited spots.