Few inventions have ever spread through a nation as suddenly, as joyfully, as the radio. Nowhere did the craze move more quickly than in the United States. In 1919, hardly a single American family owned a radio set. Within barely four years there were not just a handful of broadcasting stations in the country but more than five hundred. In 1922 – in 1922 alone – Americans spent no less than $60 million on radio sets.

It is difficult today to grasp how unlikely the radio's success once seemed. In 1920, sets were pricey, temperamental and baffling. 'Half the people who buy one will never work out which knob to turn,' grumbled one shopkeeper.

For many people, a first meeting with the radio was a deeply bewildering experience. One elderly farmer, handed his grandson's headphones, heard a dance band playing and at once thanked the musicians politely for coming. When they carried on regardless, he asked them, rather more loudly, to play a waltz instead. Receiving no reply, he took the set apart on the kitchen table, searching for the tiny orchestra he was sure was hiding inside. His grandson spent the rest of the evening putting it back together. The band, needless to say, never did play that waltz.

Everything that radio needs in order to make sense – regular programmes, printed timetables, repair shops, stations that broadcast all day – was missing in the early 1920s. Many stations broadcast for only an hour or two each evening, and some for only a few evenings a week. A set was not just a luxury but, since there was so little to hear, almost useless. Outside the big cities, listeners counted themselves lucky to catch a signal at all, and what did arrive was usually smothered in hisses, whistles and crackles from rival stations and passing thunderstorms.

Listeners who managed to catch faraway stations were treated almost as explorers. Local newspapers printed the names of enthusiasts who had heard music from a thousand miles away, and neighbours crowded into their parlours, taking turns to wear the single pair of headphones (which had to be passed from ear to ear with great care) to hear a faint orchestra playing in another state. Most sets of the period, however, could not manage such feats. Those who hoped to pick up a distant station soon learned that the only real chance came after dark; during the day, faraway signals simply faded away.

But the shortage of programmes discouraged nobody. The $60 million spent on sets in 1922 had climbed to about $350 million by 1924. Programmes began to fill the day. Newspapers printed the first radio listings, older listeners still spoke fondly of 'the wireless' – a name from the days when messages were first sent through the air without any wires – and people everywhere were humming songs about the new craze, such as this one:
Tune in tonight and don't be late,
The band begins at half past eight;
So pull your chair up, dim the light,
We'll dance around the room tonight.

A whole new vocabulary arrived with the radio. Some keen listeners proudly called themselves radio-bugs (a short-lived nickname for people who could not stop fiddling with their sets), but soon almost everyone was using expressions like on the air, tune in, sign off, static and broadcast.

The $350 million of 1924 had grown to more than $800 million by 1929. By 1930, about twelve million American homes, roughly four in every ten, owned a radio, and there were more than six hundred stations on the air. An industry that had barely existed ten years earlier had become one of the fastest-growing businesses in the country.

Much of the credit for bringing radio into ordinary homes belongs to a humble device with a curious name: the crystal set. It needed no batteries and no mains electricity, drawing all the power it required from the radio waves themselves. It could be assembled at the kitchen table from a kit costing a couple of dollars, and its heart was a tiny lump of crystal touched by a fine wire that everyone called the 'cat's whisker'.

By 1923, crystal sets were being built in countless homes, many of them by schoolchildren. The set's simplicity was its great selling point – 'If you can wind thread on a bobbin, you can build a radio,' promised one popular magazine – and its price put it within reach of almost every family. Yet it had its drawbacks. It could be heard only through headphones, by one person at a time. It could rarely reach a station more than forty or fifty kilometres away. And the cat's whisker had to be nudged patiently back into place every time someone bumped the table.

Glossary
temperamental: likely to stop working properly without warning
parlour: a sitting room in a house
static: crackling noise heard on a radio
bobbin: a small reel that thread is wound on