The first voice and music signals heard over radio waves were transmitted in December 1906 from Brant Rock, Massachusetts (just south of Boston), when Canadian experimenter Reginald Fessenden produced about an hour of talk and music for technical observers and any radio amateurs who might be listening. Many other one-off experiments took place in the next few years, but none led to continuing scheduled services. On the West Coast of the United States, for example, Charles (“Doc”) Herrold began operating a wireless transmitter in conjunction with his radio school in San Jose, California, about 1908. Herrold was soon providing regularly scheduled voice and music programs to a small local audience of amateur radio operators in what may have been the first such radio operators in what may have been the first such continuing service in the world.

The radio hobby grew during the decade before World War I, and the ability to “listen in” with earphones (as there were no loudspeakers) and occasionally hear voices and music seemed almost magical. Nevertheless, very few people heard these early broadcasts—most people merely heard about them—in part because the only available receivers were those handmade by radio enthusiasts, the majority of them men and boys. Among these early receivers were crystal sets, which used a tiny piece of galena (lead sulfide) called a “cat’s whisker” to detect radio signals. Although popular, inexpensive, and easy to make, crystal sets were a challenge to tune in to a station. Such experiments were scattered, and so there was little demand for manufactured receivers. (Plug-in radio receivers, which, through the use of loudspeakers, allowed for radio to become a “communal experience,” would not become widespread until after 1927.) Early broadcasters in the United States, such as Herrold, would continue until early 1917, when federal government restrictions forced most radio transmitters off the air for the rest of World War I, stalling the growth of the medium.

One of the world’s first scheduled radio broadcast services (known as PCGG) began in Rotterdam, Netherlands, on November 6, 1919. Other early Dutch stations were operated by the Amsterdam Stock Exchange (to send information to new members) and by a news agency that was seeking a new way to serve newspaper subscribers. Another early station appeared in Canada when station XWA (now CFCF) in Montreal began transmitting experimentally in September 1919 and on a regular schedule the next year. (The first commercially sponsored stations in Canada appeared in 1922.) The first British station offered two daily half-hour programs of talk and music from Chelmsford (near London) in 1919–20. Concerns about interference with military wireless transmissions, however, led to a shutdown until 1922, when government-authorized stations appeared, including the first London-based outlet. The first Mexican radio station aired in the capital city in 1921, though many in the country had first heard broadcasts from Cuba or Puerto Rico. By that point, stations had also appeared in Australia (Melbourne, in 1921), New Zealand (from Otago University in Dunedin, also in 1921), and Denmark (from Copenhagen, 1923).

Broadcasting got an important boost in the huge American market when about 30 radio stations took to the air in different cities in 1920–21. Most of these developed out of amateur operations, each dedicated to a different purpose. “Doc” Herrold returned to the air in 1921, but he soon had to sell his station for lack of operating funds. The University of Wisconsin’s WHA began as a physics department transmitter, but as early as 1917 it was sending wireless telegraph agricultural market reports by Morse Code to Wisconsin farmers. WHA, the first American educational outlet, probably began voice broadcasts in early 1921, though several other universities soon initiated stations with similar aims. KDKA in Pittsburgh, most often cited as the first radio outlet in the United States, had begun as the amateur station 8XK in 1916, but it was forced off the air in World War I. It reappeared on November 2, 1920, as a “commercial” voice-and-music service operated by the Westinghouse electrical manufacturer to help sell the company’s radio receivers. Westinghouse added other stations in different cities over the next two years, and General Electric and the newly formed Radio Corporation of America (RCA) soon entered the radio business as well. Detroit’s amateur operation 8MK (which debuted on August 20, 1920) soon became WWJ, the first station to be owned by a newspaper (The Detroit News). Initially seen as simply another press-supported community service, a radio station became a means of hedging bets in case the new medium proved competitive with newspapers.

Slowly, other American stations took to the air, often as auxiliaries to the owner’s primary business, such as a retail store, hotel, or record shop. The deluge came in 1922 when more than 550 new stations crowded onto the few available frequencies to build on radio’s appeal across the country. Many quickly disappeared as they could not pay the cost of operations (on air advertising was rare). Equipment was largely hand-built, and most stations operated with less power than an ordinary reading lamp. Initial studio spaces had walls covered in burlap to deaden sound and, along with a microphone, featured a piano that could be used for filling short bits of airtime. A few stations experimented with telephone lines to allow two or more outlets to carry (or “network”) an occasional presidential address or sporting event. Audiences were enthralled as radio became a national craze. Magazines, books, and even movies featured or included references to radio broadcasting.

Most other industrial nations began radio broadcasts by the mid-1920s. France (in Paris) and the Soviet Union (in Moscow) aired broadcasts in 1922. The first continuing Chinese radio station appeared in Shanghai early in 1923, when stations also appeared in Belgium, Czechoslovakia, Germany, and Spain. The pace quickened when Italy explored radio in 1924, followed by Japan, Mexico, Norway, and Poland in 1925. All these countries varied in how they authorized and organized radio services, with governments usually playing a far more central role than was the case in the United States.

Stations everywhere faced the same basic problem: what to program in order to attract and hold an audience—and how to support a continuing service financially. Radio quickly became popular anywhere signals could be heard, but how best to utilize the medium—what to place on the air, or to “program”—remained to be seen. Most early broadcasts were characterized by haphazardness, though two attractions quickly stood out: the warmth of the human voice (at first nearly always male) and almost any type of music, classical or popular, instrumental or vocal. Virtually everything on the air was live because recordings were of poor quality. Thus, a speaker or a musician could easily fill time until the next segment appeared. Only after the first few years did the notion of “programs” develop, with specific times and lengths, beginnings and endings.