Technology has been an important part of world’s fairs since the first one in London in 1851, where agricultural reapers and Colt’s revolvers were on display. But at the world’s fairs in Chicago in 1933 and New York in 1939, technology gained far greater prominence, with spectacular, larger-than-life exhibits that showcased the latest in manufacturing and communications. Even though the country was still in the depression and admission prices were high (50 cents in Chicago and 75 cents in New York), the events were enormously successful, together attracting more than 90 million visitors.

Inventors had always flocked to world’s fairs to show off their latest inventions. Automobiles, telephones, and electric lights all made their major public debuts at fairs before the 1930s. “If you were an inventor or manufacturer and you were trying to introduce a product or idea to the masses, a world’s fair was a pretty good way to do it,” says Robert Rydell, a history professor at Montana State University. But during the depression-era fairs, organizers gave scientists and corporations an opportunity to present technologies integrated into visions of a more prosperous future.

The 1933 Chicago World’s Fair, whose theme was the “Century of Progress,” stood out because of the unprecedented influence that scientists and engineers had in its planning. Led by Frank Jewett, chief engineer and vice president of American Telephone and Telegraph (AT&T), American scientists seized on the event as a chance to improve the image of technology. Exhibits included a working auto assembly line, a working model of an oil refinery, and cable cars that looked like rockets and that were suspended 60 meters off the ground. Displays devoted to math, physics, chemistry, biology, and geology were housed in the U-shaped Hall of Science, the fair’s largest exhibit building. Outside the Hall of Science was a statue depicting a robot pushing a man and a woman forward with its hands.

Companies spent millions of dollars at the 1930s fairs to install exhibits that trumpeted the power and promise of industry. At the 1939 New York “World of Tomorrow,” the list of companies showing off their newest products included all of the major carmakers; Kodak, which was demonstrating color photography; AT&T; General Electric; the Radio Corporation of America (RCA), demonstrating television; and Westinghouse, which displayed a seven-foot-tall, cigarette-smoking robot called Elecktro the Moto-Man. DuPont unveiled the world’s first synthetic fiber, nylon, in front of 3,000 women’s-club members.

But the most popular exhibit was the Futurama at the General Motors pavilion, which attracted almost 27 million visitors, many waiting in line for as long as two hours. Visitors seated in moving chairs equipped with built-in, individual sound systems peered over a futuristic model of an American city in 1960, neatly crisscrossed by well-engineered seven-lane superhighways that permitted automotive speeds of up to 100 miles per hour. The exhibit was a marketing coup for the largest automaker. According to Rydell, the enthusiasm created by Futurama helped push the federal government to build a national highway system, which it did in the 1950s.

The next world’s fair wouldn’t take place until 1958 in Brussels, Belgium. The Cold War was under way and the specter of nuclear weapons hovered over everything. The sobered mood was obvious in the Brussels fair’s theme: “Building the World on a Human Scale.” By the early 1960s, however, the space race had begun, and world’s fairs reflected a renewed optimism about technology. The futuristic-looking Space Needle symbolized the 1962 fair in Seattle, and at the 1964 fair in New York City, GM’s Futurama exhibit returned, this time featuring lunar travel, underwater resorts, and solar energy.

World’s fairs are still going on today: the 2005 World Exposition in Aichi, Japan, -began last month. But with so many other means of marketing and learning about new technology available, world’s fairs have never recaptured the excitement and hope they once generated for millions of depression-weary visitors.