Originally Posted by Don H
Even though you may be passing through the state without stopping and FOPA (federal law) allows you to do so, some jurisdictions have a history of ignoring FOPA and making the owner jump through expensive legal hoops to make the charges go away and het his handgun back. Places like Chicago, NYS/NYC come to mind.
Beyond this, the opening post indicated that they plan to STOP in each of the lower 48 states. The FOPA applies to transiting through
intervening states. One of the basic criteria of the FOPA is that possession and carry
of the firearm must be legal in the place where the journey starts and the place where the journey ends. Each time you stop to engage in sightseeing, that's a destination.
Unfortunately, you have to deal with 48 states and 48 different sets of rules, With stops planned in all 48 (lower) states, the FOPA is going to be of very limited applicability. There isn't going to be any single, simple, one-size-fits-all answer to this question. A jump say from Texas into Oklahoma might be no problem whatsoever. New York into Massachusetts? EEK! Probably not legal in either jurisdiction without a carry permit issued by that state
(they don't have reciprocity with anyone).