The first use of radio in a control tower at an airport in the U.S. was achieved in 1930 at Cleveland Municipal Airport. The Cleveland Hopkins International Airport reports that by 1932 the majority of airlines in the U.S. had equipped their planes with radio to allow contact with airports for weather and flight information.
Airport control towers rely on radio communications in order to maintain contact with flights leaving and entering an airport. The Bureau of Labor Statistics reports that when an airplane is around 50 miles from an airport, communications are passed over to the airport control tower to guide the plane to the landing strip.
The Bureau of Labor Statistics explains radio communications are split into different areas within an airport. Outgoing flights are ordered for take-off and for permission to taxi to runways, while incoming flights are ordered and given permission to land by another set of air traffic controllers using radio communications.
According to the Chicago O'Hare Air Traffic Control website, radio was first used to send a message across the Atlantic Ocean just two years before the Wright Brothers completed the first heavier-than-air flight in 1903.