Wayne Thornton started Thornton Plastics Company in 1948. He was the sole-owner for many years. The first product line consisted of Christmas bells, screwdriver handles, plastic spoons and plastic tumblers. In 1955 a new product line was created. It consisted of clear and amber colored plastic vials. The vials were sold mainly to pharmacies and hobby stores.

In 1960 the company was incorporated. With a steady increase of vial sales, the other product lines were dropped. The vial product line grew to a total of 10 different sizes of vials, both clear and amber colored, ranging from a 3½-dram to a 50-dram vial (.125 ounces in a dram). In 1997, the amber vials were dropped from production with focus on the clear transparent vials.

In 1997, Wayne Thornton founder of Thornton Plastics passed away. The company was managed by his daughter, Renee Thornton, for many years. 

In 2005, Briton C. McConkie, Wayne Thornton's grandson, became the President. The company has recently expanded their snap-cap vial line and expanded into threaded plastic jars.