I agree with the above. You can practice in whatever state you want as long as you obtain a medical license. I believe there a lot of factors that keep people in their training area. I believe one of the biggest reasons is that you get comfortable in your hospital. You know all the other doctors, the department, the nurses, the orders, other docs in the other fields. Most of the times groups who are looking to hire seek you out b/c they get to know you after your residency. If you have family then that is a big factor b/c you might not want to relocate if you are married, if your spouse has a good job, if the children like their school, parents are around to help with the kids.