If no Mississippi university offers your major, you can go elsewhere at in-state tuition rates

    Between Ole Miss and Mississippi State a prospective college student has his choice of just about any major out there. Almost any major, but not every major.
    Some majors just aren't available in Mississippi. For example, no Mississippi university offers majors in either petroleum or nuclear engineering.
    But that doesn't mean students wanting to major in some of these more esoteric fields have to pay expensive out-of-state tuition. A consortium of Southeastern state universities known as the Academic Common Market allows students from most Southeastern states to attend out-of-state universities at in-state rates if they major in a program not offered by a university in their home state.

    The course I've heard mention of in the past is the PGA Golf Management course at Mississippi State. Other State courses which attract Common Market participants from out of state include Broadcast Meteorology, Aerospace Engineering, Veterinary Medicine, Agricultural Information Science, and Poultry Science.
    At Ole Miss popular courses include Geological Engineering and Forensic Chemistry.
    Taking advantage of this program isn't as simple as simply showing up at one's desired out-of-state university and demanding a tuition break. One must fill out an application and be certified by one's state as eligible to participate. But I suspect it's a fairly painless process. However, things do take time, so don't wait until June if you are wanting to start school in September!
    North Carolina doesn't participate in the Common Market. Florida and Texas participate only at the graduate level.
    This PDF report on Mississippi activity in the Academic Common Market does a really good job of showing where both Mississippi and out-of-state students are going as a result of the Common Market. It's worth looking at, even though it hasn't been updated since 2011.
    One big question that comes to mind is what happens if a student changes his mind mid-way through his coursework? From the FAQ:

"Most ACM institutions will not require you to pay back tuition for the years that you received ACM benefits if you change your major or program to one that is not approved for the ACM or is available in your home state. However, if you change your major during a semester, the institution may charge you the out-of-state tuition rate for that semester. If you change your major to a different program that is included in the Academic Common Market, you must be recertified by your state coordinator."

    Notwithstanding the above, I would resist the temptation to abuse the program. I suspect they reserve the right to demand reimbursement in cases where they believe a person declared and later changed a major simply to evade tuition.
    So if Mississippi doesn't have your major, don't worry about having to pay out-of-state tuition. With a little advance planning, you won't have to.