1927: AT&T provides the first demonstration of long distance television transmission in the United States, with transmission via wire from Washington, D.C., to New York, and via radio from Whippany, N.J., to New York. The demonstration used electromechanical equipment and scanned at 50 lines of resolution, 16 times per second.
1929: AT&T researchers Lloyd Espenschied and Herman Affel file a patent application for coaxial cable, the first broadband transmission medium, which was able to carry the signals needed for good-definition television over a long distance.
1937: AT&T experiments with transmitting motion pictures over the New York-Philadelphia cable at the previously impossibly large bandwidth of 1 million hertz. (By comparison, the 1927 broadcasts were transmitted at 22,000 hertz, and a modern broadcast channel uses 6 million hertz.) After this experiment, AT&T discontinues work on electromechanical television, as it seems clear that the future will lie with all-electronic systems invented independently by Vladimir Zworykin and Philo T. Farnsworth. AT&T continues to work on television transmission, expecting that that once commercial television begins, broadcasters will use AT&T to provide the circuits to transmit programming to stations across the country. AT&T already provided a parallel service for radio broadcasting.
1940: AT&T transmits the 1940 Republican convention from Philadelphia to New York, where it is televised to a few hundred receivers over RCA's experimental television station.
1947: AT&T completes a microwave-relay transmission system between New York and Boston, and connects it to the existing New York-Washington cable to provide television-networking facilities from Boston to Washington.
1948: AT&T transmits the Republican and Democratic political conventions in Philadelphia to stations from Boston to Richmond, Va.
1951: AT&T completes construction of the first transcontinental broadband-communications network. President Harry Truman's Sept. 4 address to the United Nations/Japan peace treaty conference is the first live transcontinental television broadcast.
1954: AT&T provides the networking facilities for the first color network broadcast, the Tournament of Roses Parade.
1962: AT&T's experimental Telstar satellite provides the first live transatlantic television. A variety of programs are sent in both directions, including French singer Yves Montand, a British cooking show and a press conference by President John Kennedy.
1983: AT&T launches its first Telstar III domestic communications satellite. Telstar III and the later Telstar IV satellites provide additional networking services for television. AT&T exits the satellite business in 1997.