The frozen carbonated beverage (as they refer to it in the business) came about in 1959 when Omar Knedlik, a Dairy Queen franchise location owner, started selling bottled sodas straight from his freezer after his soda fountain went on the fritz. Customers responded so well to the slushy drinks that the idea was born to start selling such a beverage on a regular basis, even after the machine was fixed. Unfortunately, building a machine capable of creating such a thing was beyond Knedlik's abilities. He turned at last to the John E. Mitchell Company, a Dallas manufacturer, who went to work on the idea.
The trick was to freeze a carbonated drink mix, not so much as to render it solid, but only that it retained the desired 'slushy' quality necessary for success. The resulting machinery is able to pull off the entire thing: flavored syrup and carbonated water (which are what all sodas are basically made of) are combined and frozen within a pressurized, tumbling mechanism - which, because of the constant movement, prevents the mixture from freezing completely, as well as keeping the ingredients from separating.
Throughout the early 1960's the machines were offered for sale to various restaurants and retailers across the nation with limited success. In 1965, however, the burgeoning 7-Eleven drive-in stores purchased three of the machines to test-market the product, and to everyone's relief it was a big hit. By May of 1967 nearly every 7-Eleven had such a machine, and the company decided to create their own brand - Slurpee, which remains a hit to this day. Although a variety of flavors are offered to the modern consumer, originally only Cherry and Coca-Cola were available; enterprising kids would mix the two for a concoction often known as a Suicide.
Slurpee's competitor (more or less) is Icee, which can be located across the country in stores other than 7-Elevens. The Icee machines are recognized by children easily because of their long-standing polar bear mascot, as well as the red-and-blue logo.
Other similar frozen-beverage brands are:
-Frosters, in Circle K stores in the U.S. & Mac's in Canada;
-Sloches, in Quebec, Canada;
-Granizados, in Latin America.