After the First World War, the American government found itself with a large surplus of Curtiss JN-4 biplanes (known as 'Jennys'). Flying was not yet regulated by laws and licenses, and so the planes were simply sold to anyone who wanted them. The Jennys were known to go for as little as $200, which, although a lot more money in those days, was a fraction of the original $5,000 production cost. Many of the buyers were former pilots in the war who wanted to keep flying, but quite a few of the others who purchased planes had never actually flown before. In fact, this would be the first major form of civil aviation.
Quickly, this new influx of planes among civilians lent itself to entertainment. Airspace was open to any plane at this stage, and so at first pilots simply made money by going from town to town and offering ten-minute rides to the locals. This worked for a while, until planes became widespread enough for basic flight to become largely unremarkable. At this point, people began to do flashier things in the air - namely, all sorts of creative and crazy stunts right on top of the wings of the planes.
It is not clear how the term 'barnstorming' emerged. One theory holds that it was named for earlier groups of travelling actors who had put on plays in barns. Another, more plausible, argues that it was based on the usual way in which the shows were announced to the local townspeople. Pilots would fly over a town to make themselves noticed, and then land at a nearby farm and ask the farmer for the temporary use of the fields as a runway. Then, often the planes were met by rural towns with tremendous excitement in anticipation of the show.
The phenomenon was a team effort throughout; the barnstormers consisted of both pilots and stuntpeople. They followed the example of brief flying exhibitions put on by the Wright brothers and Glen Curtiss in the first decade of the 20th century, but took it much further. Aerialists performed 'wing-walking', sometimes in costume. They transferred planes in mid-air, often via a small, secured post in the centre of the wing.
And it got more elaborate than that. Barnstormer Al Wilson shot golf balls. Mabel Cody danced. Gladys Ingle shot arrows at a target (although didn't necessarily hit it). Ivan Unger and Gladys Roy played tennis - complete with a tiny net stretched across the wing directly above the cockpit. Jack Shack hung from a trapeze - by his teeth. Eddie Angel did what was effectively a free-fall, for thousands of feet, holding a pair of flashlights.
One notable aspect of barnstorming was that, in spite of its time, a substantial number of women and African-Americans took part. This was partially due to the tendency for larger groups (including some families) to work together for a barnstorming show. These performances, which were eventually labelled 'flying circuses', usually involved several planes and many stuntpeople. They were better-organized than the smaller teams, and even notified towns ahead of time to schedule their shows. Probably the most well-travelled was the Ivan Gates Flying Circus, which went to every state that existed at the time, as well as to several international locations.
Often barnstorming was quite lucrative, in part because it still offered rides to civilians. It was notable also for its role in training pilots; historian Don Dwiggins points out the widespread belief that, during the height of barnstorming's popularity, the Gates Flying Circus trained more than the Army and Navy put together. The notorious Charles Lindbergh was among the pilots who started out in barnstorming.
Obviously, it was also a dangerous pursuit. As barnstorming's popularity grew, the performances became increasingly elaborate and risky. In 1924, stuntperson Rosalie Gordon's parachute was tangled in the landing gear of a plane; she was rescued by fellow barnstormer Clyde "Upside-Down" Pangborn from the Gates Flying Circus. Most barnstorming accidents, however, ended less happily. Although it is unclear just how many barnstormers were killed or injured while performing, the negative publicity started to dampen the huge appeal that barnstorming had had.
It might still have continued for a while, however, if it hadn't been for two things the American government did in the later half of the decade. First, it stopped selling Jennys to the public; the existing ones were in decay, and there was no other inexpensive source of aircraft that could keep barnstorming as common as it had been. Second, in 1927 major new restrictions on the uses of aircraft and airspace were put into effect. While they didn't make barnstorming per se illegal, so many of the tricks were outlawed that barnstorming lost nearly all of its appeal.