Radio operation in the U.S. resumed in 1919 after WWI was over. In 1920 the Radio Corporation of America was formed by the Navy Department, American Marconi and General Electric. This established them as the dominant American radio manufacturer.
RCA quickly moved into commercial broadcasting, and in July 1921 broadcast it's first program - a Jack Dempsey professional fight held in Hoboken, NJ. The broadcasting boom of 1922 established their leadership in both manufacturing and broadcasting.