https://www.law.cornell.edu/uscode/text/18/926A
Although already discussed and explained (acknowledge I am not obliged to do so again)
This only applies in certain circumstances. If my CCP is recognized in a state I am traveling thru (which is mot of them) it does not apply.
If I am going from say Va (where I can legally carry) o Nh (where 8 can legally carry) different rules apply because I have to drive thru MD, DE, NJ, NY and MA. Where I am not legally allowed to have a firearm
Acknowledge you have been answered. Again.