Peanut Butter provided an inexpensive, high protein alternative to meat for soldiers during WWII. During the war, jelly (also on the ration list) was added to peanut butter by the soldiers to make it more palatable.  When the soldiers came home from war the continued to crave the taste of peanut butter and jelly, and the sandwich became popular among all people.  Peanut Butter and Jelly sales soared in the US after the 1940’s.  Also while almost every other beloved food was rationed in 1943, Peanut Butter did not have to be rationed.  Since it was so readily available, people ate it.  And subsequently wound up loving it.  Peanut Butter was most likely mixed with Jelly, or fruit, or even sometime mayonnaise to extend its use before the War, but it wasn’t until then when it truly caught on.

By the age of 18, the average American has consumed at least 1,500 peanut butter and jelly sandwiches!