A Southland employee stands in front of the ice dock on Edgefield at Twelfth, which would become the first 7-Eleven store. Photo courtesy of “Oh Thank Heaven! The Story of the Southland Corporation,” by Allen Liles

This coming Tuesday is July 11, which means 7-Eleven stores across the globe will offer free small Slurpees from 11 a.m.-7 p.m.

In case you’ve forgotten, or if you didn’t know, the Southland Corp. and 7-Eleven were born in Oak Cliff.

It was the first company to sell coffee in paper cups to go and the first to offer self-serve soda fountains. In 1959, Dean Sperry and Omar Knedlik of Dallas-based manufacturing company E. Mitchell Co. invented the Icee machine, which served frozen carbonated drinks. 7-Eleven bought three Icee machines in 1965, and they were such a hit that a few years later, nearly every store had one. The Stanford Agency named it the “Slurpee” for the sound it makes coming out of the straw, and 7-Eleven bought radio ads to promote that now iconic treat.

Read all about Oak Cliff’s place in convenience story history here.