The former U.S. territory of the Canal Zone first issued license plates in 1910, and this continued until the Canal Zone was returned to Panama in 1979. A single plate was issued for all years. The country of Panama also issued Canal Zone license plates for United States citizens that lived in Panama but worked in the Canal Zone, but these plates have the country name "Panama" clearly showing on them. Since reciprocity for license plates between the Canal Zone and Panama did not exist until 1950, old photos often show local vehicles with two different license plates mounted on the vehicle.