Help with how picking a state works

Foodsman wrote:
Maybe a stupid question, but how does the DMV know you're using mail forwarding if you have a street address?

Computers. Mail forwarding company addresses are not a secret. Many data bases specifically flag those addresses. Almost any financial company or insurance company will have those addresses red flagged due to both Patriot Act concerns and general credit reasons. It is pretty hard to repossess a car or determine the insurance risk from a post office box. Plus, full time RVers are not the only people who use PMBs (think people who don't want to be found).