August 17, 1951: The first telephone call is placed on AT&T's new microwave radio-relay skyway, the first facilities to transmit telephone conversations across the United States by radio rather than wire or cable.
The new backbone telephone route, at the time the longest microwave system in the world, relayed calls along a chain of 107 microwave towers, spaced about 30 miles apart. AT&T spent about three years building it at a cost of $40 million.
The system was designed to carry television signals as well as telephone messages, and less than three weeks after the first phone call, it did just that. On Sept. 4, the largest single television audience to date - estimated at more than 30 million people - saw and heard President Harry Truman open the Japanese Peace Treaty Conference in San Francisco. The nation's first coast-to-coast telecast, this broadcast was made possible when AT&T met a U.S. State Department request to advance the TV opening of the new system by a month.
The historic program went off without a hitch. The New York Times reported that "the image reproduced on screens in the New York area, nearly 3,000 miles from the scene, had excellent clarity and compared favorably with programs of local origin. The contrast was of first-rate quality and there was no distortion."
In a letter to AT&T President Cleo Craig, Federal Communications Commission Chairman Wayne Coy wrote, "Moving forward the date for the opening of the transcontinental microwave radio relay for television - makes your accomplishment all the more significant. I appreciate the zeal, the enterprise and all the extra effort that made this triumphant event in communications history possible."