I would practice my theories and psychology and opinions in ANY state I come to. I do not think it's "only for CA".
I did notice however, as a young man hitch-hiking across America in 1982, one difference in the way people think and respond:
I was going through a rural part of Mississippi or Alabama. I saw a one-room school house, all closed down (like perhaps currently used as a grange hall or something, but you could tell it had been a one-room school house at one time). I thought: "That looks like a good place to detect!" There were no fences, no signs, no nothing. And presumably, it was a public building. I sat my back-pack down on the picnic bench out from, and proceeded to pull out my detector, to piece/assemble together to hunt. No sooner did I have it set up, and was checking my battery strength, than a sherrifs car pulled up! Evidentally they'd gotten a call from a curious neighbor, who saw someone in the vicinity of this school/center thing. I forget what he said to me (and whatever it was, it didn't have anything to do with metal detecting, as that wasn't the point). It was just that ........ culturally, ... people in those "back woods southern areas" tend to "look out at any outsiders with suspicion". You know, like a sort of "good old boys" mentality. For example: when the put me in the squad car (because they were going to drive me to the county line), believe it or not, the MAYOR (or council man or alderman or something) was sitting in the front seat of the squad car, accompanying this "mayberry RFD" sherrif on his rounds. It was like a scene straight out of "mississipi burning" movie, or "dukes of hazzard" or some such cultural thing. Kinda funny.
Anyhow, that sort of scene would never happen in CA. But that culture of psychology has nothing to do with the act of metal detecting. It's just pervasive of all people's, in their view of outsiders, or seeing things outside the cultural norm ("long haired CA hippy" types perhaps was their attitude?). So I can see, to a degree, that yes, states differ. But once you account for the "way to act" psychology, then the other part of this discussion (of whether we all "need permission" to hunt parks with no specific rules saying you can't), then I would apply that, across all 50 states. But yes, of course, DUE DISCRETION and OBVIOUS COMMON SENSE of your surroundings, the culture, etc... are all in order.
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