Third US national radio conference. Group of three US pioneers of radio in the USA at a conference convened by US Secretary of Commerce (and later US President) Herbert Clark Hoover (1874-1964). Hoover is at at far right. From left to right, the three pioneers are: Charles Francis Jenkins (1867-1934), David Sarnoff (1891-1971), and George Owen Squier (1865-1934). Jenkins had pioneered radio and television improvements. Sarnoff was part of the Radio Corporation of America (RCA), becoming its president in 1930. Squier was Chief Signal Officer during World War I. Photographed in Washington DC, USA, on 7 October 1924.