Yellow Margarine

Via Ezra Klein, a history of coloring margarine. New York was one of the states in which Parkay margarine was sold white, with a packet of coloring which you kneaded into the product to turn it yellow. I remember my mother doing this, so it must have been right at the end of WWII.  I'm sure mom, being a true believer in the virtues of dairy, was not using margarine willingly.