Not only is it state specific, but it is also school-specific. Where I live, I lived in the state for 8 years, and they still made me petition for residency just because I moved here 8 years ago for graduate school (educational intent for moving here in the first place). They gave me resident tuition, mind you, but I had to fill out a lot of paperwork. Another school in this state just went by what I had declared. There are a lot of cases I know where a school has given special consideration to a student for recruiting purposes. Texas is a good example where they are kind to newcomers.
If you are military or married to a resident, it will make a big difference.
OP, maybe I missed this, but why are you a person with out a state?
To people still interviewing, don't say, "Yeah I'd only come here if you considered me as a state resident. Medical school is not a good investment if you have to pay 40K a year for tuition."
The main thing that I can tell you is that if you are going to a state school, they will spell out their residency definition for you, most likely on their website.
Just to throw a little diversity into the discussion, most of Big 12 country is "non-resident if you didn't go to high school here until proven otherwise, and even then, you better have some damn good proof."
I find it ironic that they want you to prove that you intend to state there if you come from oos, but there is no such expectation for the 80% of the class who are in-state.
It is this reason specifically that I support a federal driver's license in which there is a uniform policy throughout the country for residency determination. Under current rules, you could potentially be a resident of multiple states or no states. AMCAS makes you claim a single state, but I had a school challenge me during the interview process and kicked me out of their pool. I was like, "Well that's great, you should tell whatever state you think I belong to that I am in-state there."