The first World’s Fair to take place in the United States was held in Philadelphia in 1876, and also celebrated the 100th anniversary of the country’s founding. Officially known as the International Exhibition of Arts, Manufactures, and Products of the Soil and Mine, inventors from the 37 countries participating in the fair showed off their latest innovations, including a Scottish-born professor of vocal physiology at Boston University named Alexander Graham Bell.

After years of attempts, Bell achieved his goal of transmitting sound over a wire, and on March 7, 1876, obtained his first U.S. Patent for a device he labeled as “Improvement on Telegraphy”—now better known as the telephone. Though he had tested the technology with colleagues in Boston, Bell’s first public demonstration of his telephone took place a few months later, on June 25, 1876 at the Philadelphia World’s Fair.

It’s easy to take the zipper for granted today, but before it was invented, getting (and staying) dressed involved securing clothing with ropes, ties, buttons or other fasteners. Its earliest iteration, known as the "automatic continuous clothing closure" was patented in 1851 by Elias Howe: the inventor of the modern lockstitch sewing machine (for which he won a gold medal at the 1867 Paris World’s Fair). But Howe never marketed his zipper, and it didn’t take off.

Then, in 1893, inventor Whitcomb L. Judson received a patent for his “clasp locker” shoe fastener, and immediately partnered with businessman Colonel Lewis Walker to launch the Universal Fastener Company and manufacture his invention. The "clasp locker" debuted at the 1893 Chicago World’s Fair, then renamed the “zipper” in 1923 by B.F. Goodrich when the company started used the fasteners on their rubber boots.

Along with the zipper, the Garis-Cochran Dishwashing Machine was also first introduced to the public at the 1893 Chicago World’s Fair, in a display drawing crowds curious about the contraption capable of thoroughly washing and drying 240 dishes in two minutes. The crowd-pleasing exhibit was more than a decade in the making. In 1883, Ohio entrepreneur Josephine Garis Cochran grew frustrated with the amount of time it took to clean up after dinner parties, reportedly saying, “If nobody else is going to invent a dishwashing machine, I’ll do it myself.” And she did.

By the end of 1886, Cochran had received a patent for her “dish washing machine” (which also included a system for cleaning flatware). And though many people were impressed by her invention, potential investors made it clear that they would only be on-board if Cochran stepped down and handed over control of the Garis-Cochran Company to men. Unwilling to do so, it wasn’t until the 1893 Chicago World’s Fair that Cochran had the opportunity she needed to get her dishwasher in front of the right audience. After that, orders for her product began flooding in from restaurants, hotels, hospitals and colleges, and in 1898, Cochran opened her own factory.

One of the biggest challenges that arose during the early days of electricity was getting it from the power source to an individual device. By the 1880s, entire houses were being wired for electricity, but electrical appliances had to be connected to the home’s main power source directly, posing serious safety risks to members of the household.

That changed in 1904, when Harvey Hubbell—who had previously invented the pull-chain electrical light socket—patented the first detachable electric plug in the United States. Consisting of two round pins with annular detents at the tips, Hubbell's design was meant to keep a plug safely in its socket, avoiding dangerous electrical short circuits and the resulting shocks. Hubbell first displayed his invention at 1904 World’s Fair in St. Louis, and within 10 years, his plug and socket changed the way Americans used electricity.

The development of television took place over the first decades of the 20th century, but made its official debut on April 20, 1939 at the New York World’s Fair. On that day, the dedication of the Radio Corporation of America (RCA) Building at the fairgrounds in Queens was telecast eight miles away to the company’s headquarters in Manhattan. Ten days later, the fair opened to the public, and the following day, RCA began selling television sets. May 1, 1939 saw another television milestone: the launch of a regular television broadcast schedule on the National Broadcasting Company (NBC), which was owned by RCA.

Fairgoers could take what was advertised as “America’s first television tour” (presented by NBC), where they would learn about the history of the medium, as well as the science and engineering that made its broadcast possible. But despite the buzz surrounding the new technology, it took some time before television sets were accessible to middle-class American families. Prior to 1947, only a few thousand of the country’s households owned TVs. But within five years, the presence of television in the United States increased dramatically, with TV sets in 12 million homes in 1952, and earning its place in half of American households by 1955.

World’s Fairs continued to be held throughout the 20th century, including in Knoxville, Tennessee in 1982. The fair counts the Rubik’s cube and Cherry Coke among its best-known inventions, but one technological development took a bit longer to catch on: the touchscreen. Although research into touchscreens began in the 1940s, and they first gained traction in the 1970s, it wasn’t until the 1982 World’s Fair that the general public was introduced to this futuristic technology, and had a chance to try it out for themselves.

In the age of smartphones, it’s easy to identify the touchscreen demonstration at the World’s Fair as a significant technological turning point, but according to Jack Neely, executive director of the Knoxville History Project and crowd controller at the World’s Fair, that wasn’t apparent at the time. “It was...one of those things you had to look fast to notice,” Neely told the University of Tennessee Daily Beacon in a 2017 interview.