CA state law requires that fixed blade knives be carried openly, or not readily accessible (i.e. buried in a backpack). But, local law can vary widely. I carry a padded SASE in case there's a problem with my pocketknife. It may be prudent to carry a collapsed prepaid shipping box for the same reason.
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Hope for the best and prepare for the worst.

The object in life is not to be on the side of the majority, but to escape finding oneself in the ranks of the insane