18 U.S. Code § 926A - Interstate transportation of firearms
Notwithstanding any other provision of any law or any rule or regulation of a State or any political subdivision thereof, any person who is not otherwise prohibited by this chapter from transporting, shipping, or receiving a firearm shall be entitled to transport a firearm for any lawful purpose from any place where he may lawfully possess and carry such firearm to any other place where he may lawfully possess
and carry such firearm if, during such transportation the firearm is unloaded, and neither the firearm nor any ammunition being transported is readily accessible or is directly accessible from the passenger compartment of such transporting vehicle: Provided, That in the case of a vehicle without a compartment separate from the driver’s compartment the firearm or ammunition shall be contained in a locked container other than the glove compartment or console.
RED: This means you must be legal to own that gun in the state you start in, and legal in the state you are going to end up in.
So, if the gun is legal in North Carolina, but NOT legal in CA, it would not be legal under the Code. And that is all I will say on this...
There is NO stipulation that you must transport via interstate hwys, you could legally do it on county roads.
MOST STATES, would have NO problem if you stopped to fillup, or have something to eat. Some states would consider a motel stop OK, since once you enter the hotel/motel it is considered a part-time residence. (BUT THAT CAN BE INTERPRETED BY STATE LAWS AND COULD CAUSE PROBLEMS.)
At one time, NY state was arresting people who were flying LEGALLY with a gun in their checked baggage and stopped over either to switch planes and they left the airport with their baggage and gun, or were stranded in NYC with their baggage and gun. SO it can get very tricky. (Not sure if they continue to do so due to lawsuits. But NOT sure).
However, that is why it is desirable to avoid some states.
Another example was before the new laws in IL, someone transporting a gun per Title 18 in the northern part of the state might encounter problems you would not encounter in southern IL.
And NJ used to be notorious for arresting people tranporting guns via Title 18; state troopers would arrest, hold, but the prosecutor would just throw it out. They were sued many times since it was total harassment by the state troopers.
So even though Federal law allows it, some states will push it to the max and harass you which will end up costing time and expense.