The first flickering shadows of television were already in the ether before radio was well established. In 1923, Vladimir K. Zworykin, an employee of Westinghouse, patented the icono-scope television picture tube. Four years later, at about the time when NBC was organizing its radio network, Philo Farnsworth improved the system and patented the dissector tube. While others had experimented with ways to broadcast an image, these two independent inventors share credit for the birth of all-electronic television transmission.

The Great Depression of the 1930s slowed down television development, but the 1939 World's Fair in New York gave Americans their first look at the medium that would dominate the second half of the twentieth century. The Radio Corporation of America (RCA), owner of the National Broadcasting Company (NBC) and its radio networks, sponsored a Hall of Television that gave fairgoers a glimpse of the future...