Radar, a system that the British initially developed for air defense in the era preceding World War II, revolutionized air traffic control.
In 1946, the U.S. Civil Aeronautics Administration used a radar system developed for the Navy to open a radar-equipped airport tower for demonstration purposes, according the FAA.
At the Washington Air Route Traffic Control Center in 1955 (shown here), standing controllers are using surplus Navy video generator equipment that presented radar data on a horizontal surface.
Across this surface, controllers moved plastic "shrimp boats" indicating aircraft, much as similar markers had earlier been used on maps.
Click here for the FAA's complete photo history of air traffic control in the U.S.