I have an academic interest in drug trafficking patterns, but I don't know very much about the US situation; however isn't much of the US supply smuggled in over land from Mexico? That would make it quite logical for areas near borders to have high quality supply.
I haven't smoked in years because it doesn't agree with me anymore, but when I did, the stuff from Mexico tended to be lower quality. The good stuff was usually local and grown with care. Think industrial versus local produce.
