Tea has been around for nearly 5,000 years, and, according to legend, was discovered in 2737 BC when tea leaves blew into Chinese Emperor Shen-Nung's pot of boiling water. Tea gradually grew in demand, becoming wildly popular in Europe and the American Colonies in the 1600s.
Hot tea has been served in America for hundreds of years, but iced tea is a relatively new variation -- especially popular in the Northeastern and Southern states. Its invention has been credited to tea merchant Richard Blechynden at the 1904 World's Fair in St. Louis. Blechynden had planned to give away free samples of hot tea, but no one wanted the samples when a heat wave hit, so legend has it that Blechynden dumped a load of ice into the batch of tea he had prepared. The cooler drink was a hit with the World's Fair's thirsty crowds, and a classic was born.
However, there are Southerners who hotly contest Blechynden's "invention," claiming cold green tea punches that became popular in the South in the early 1800s were the first transition from hot tea to iced. These were potent brews made with green tea and large amounts of alcohol, such as brandy, rum and champagne. Toward the end of the century, punch recipes without alcohol began appearing.
While Southerners had access to ice packed in straw and shipped from frozen lakes in the North, putting tea over ice in glasses doesn't appear to have caught on until after the development of refrigeration allowed people to make ice without impurities.
In the 1900s less expensive black tea supplanted green tea as the cold tea of choice. Iced tea became more commonplace, and then Prohibition in the 1920s turned it into the staple of every table in the South.