Radio broadcasting is beyond it's 80th anniversary. It has been the stepping stone to many other significant technological advances that truly benefit mankind. Unlike it's abhorrent sibling, television, radio technology as well as radio broadcasting have brought the entire world closer together. At the beginning of the 1990's, before internet radio evolved, there were 26,000 radio stations worldwide.
Also by the 1990's in the U.S.A., 12,000 commercial and educational AM and FM broadcast outlets reached 99 percent of all households, and less than 1 percent of these households had fewer than 5 receivers. It's noteworthy that anyone over the age of 80 was born into a world of no radio, although the experimentation by some during the early years of this century was quite exciting.
There are many people who contributed to, and are largely viewed as being responsible, for this medium. Guglielmo Marconi, in the 1890's, was the first to use electromagnetic waves to transmit and receive messages. James C. Maxwell and Heinrich Hertz were the real pioneers of electromagnetic waves, proving that they exist and defining some of their most fundamental properties. Marconi built on their findings and developed the first wireless telegraph, sending Morse code and other coded messages. With the development of the diode tube in 1904 by J. Ambrose Fleming and the triode tube by Lee de Forest in 1906, early innovators like Reginald Fessenden of Massachusetts began experimenting with voice transmissions. This set the stage for the contributions of the pioneer who has been largely credited with the development of present day FM broadcasting, Edwin Armstrong. His development of superheterodyne circuitry vastly changed the face of receiver technology, and during the 1920's he developed a "static-free" mode of broadcasting that we have come to know as FM, or frequency modulation. Frankly, it is the hard work of these early broadcast scientists and engineers that makes it possible for radio and television broadcasters to exist today.
Largely overcredited by modern braggadocio marketing hypesters as the "inventor" of modern broadcasting, it was David Sarnoff who conceived of the mass production of radio receivers so that the public could be the direct beneficiaries of the radio transmission of music, news, and information. Sarnoff was focused on the sale of receivers being the lit fuse to the advertising explosion that has molded radio and completely swallowed television in the 21st century..
The first AM broadcast stations in the U.S. appeared in the1920's. However, the industry was without regulation and bedlam soon set in. Attendees of the National Radio Conference in 1925 appealed to the Secretary of Commerce to regulate frequency, power assignments and hours of operation, but the Commerce Department lacked the power to control this new industry. In 1926, Congress, at the request of President Coolidge, passed the Radio Act of 1927 and formed the Federal Radio Commission (FRC). Within months of its formation, the FRC established the standard broadcast band (500-1500kc) and 150 of the existing 732 radio stations were forced to cease operation. As a result of the initiation of proper regulation, the listening public responded to interference free reception of programming by purchasing millions of receivers. Radio flourished during the depression years of the 1930's. After all, many receivers were already in place before the market crashed, and radio was free. In fact, President Roosevelt used radio extensively in communicating with the public as he faced the ominous task of rebuilding the country's economy. It was under his direction that Congress passed the Communications Act of 1934, establishing the Federal Communications Commission, to oversee and regulate all electronic forms of communication, including both broadcast and wire. Originally proposed to the FCC in 1938, Edwin Armstrong's static-free alternative to AM broadcasting, FM, was approved by the Commission in 1940. But a wartime freeze on any new station construction prevented the new technology's implementation until 1946. By then, the development of television was well underway, and the idea of a second radio band was not well received. In fact, during the 1950's the number of FM stations decreased from approximately 600 to 500.
The rise to dominance of the radio listening audience by FM radio was not fast and furious. Through a series of changes, including the authorization of stereo broadcasting in 1961 and requirement that holders of AM-FM combinations in large markets refrain from simulcasting their AM programming for at least 50 percent of the day (recently rescinded), FM has slowly become the dominant force in radio broadcasting. It took until the late 1970's for FM listenership to equal that of AM. By 1990, FM's percentage of listenership has risen to over 70 percent of all listeners, and it is unlikely that this will change in the near future. Today, the number of commercial FM stations on the air and under construction exceeds that of AM, with an additional 1700 educational FM's also broadcasting.