One of the good things that came out of FOPA.
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.http://www.law.cornell.edu/uscode/18/usc_sec_18_00000926---A000-.html Some people interpret this to mean that you can keep an unloaded firearm and boxed ammo in your trunk (inaccessible from passenger) but not necessarily locked in a separate container. If you don't have a trunk than you can have your unloaded gun in a hard container locked in your passenger compartment (But not in glove box or console). Some people say its best to keep the locked container in the back of the vehicle (more inaccessible?).
Super safe people lock their unloaded guns in hard containers in the trunk, plus put ammo in locked hard containers.