I've never heard of a sorority giving priority or saving spots for in-state gals. I'd say, if anything, you have the advantage being from out of state-you'll have more to talk about during rush than just "so whats your major?"
Although I suppose it would be possible for a college somewhere to have this policy you should be able to to direct any questions to someone @ the college/university where you are rushing. Just look up the rush information on their web site & if all else fails send an email to whatever email address they provide for questions.