Although tea had been served for years both hot and cold it did not become commercially popular until 1904. At the 1904 World's Fair in St Louis, the summer was so hot that people went in search of cold drinks. For some reason the popularity of iced tea was sealed that summer. There are many stories of iced tea being "invented" that summer but the drink is mentioned in cookbooks before that time.
According to WhatsCookingAmerica.net
1879 - The oldest sweet tea recipe (ice tea) in print comes from a community cookbook called Housekeeping in Old Virginia, by Marion Cabell Tyree, published in 1879:
"Ice Tea. - After scalding the teapot, put into it one quart of boiling water and two teaspoonfuls green tea. If wanted for supper, do this at breakfast. At dinner time, strain, without stirring, through a tea strainer into a pitcher. Let it stand till tea time and pour into decanters, leaving the sediment in the bottom of the pitcher. Fill the goblets with ice, put two teaspoonfuls granulated sugar in each, and pour the tea over the ice and sugar. A squeeze of lemon will make this delicious and healthful, as it will correct the astringent tendency."
If Ms. Tyree's recipe doesn't appeal to you try this simple ice tea recipe....
Easy Lemonade Ice Tea
6 small tea bags
1 1/2 cups sugar
1 quart boiling water
1 (6 ounce) can frozen lemonade concentrate
1 (6 ounce) can frozen limeade concentrate
1 Let tea bags steep in boiling water (approx. 5 minutes).
2 Remove tea bags and add sugar.
3 Add frozen juices and enough water to make 1 gallon.
4 Pour into glasses over ice.
recipe found at http://www.food.com/