The soft-serve formula was first developed in 1938 by John Fremont “J.F.” “Grandpa” McCullough and his son Alex. They convinced friend and loyal customer Sherb Noble to offer the product in his ice cream store in Kankakee, Illinois. On the first day of sales, Noble sold more than 1,600 servings of the new dessert within two hours. Noble and the McCulloughs went on to open the first Dairy Queen store in 1940 in Joliet, Illinois. It closed in the 1950s, but the building at 501 N Chicago Street is a city-designated landmark.
Since 1940, the chain has used a franchisesystem to expand its operations globally. The first ten stores in 1941 grew to 100 by 1947, 1,446 in 1950, and 2,600 in 1955.Wiki