What is the origin of grinder, as in sandwich?

You might be aware that a substantial sandwich, often on an elongated roll of Italian or French bread, is referred to by different names in different parts of the US. The first term used was poor boy, meaning that it was a 'meal even a poor boy could afford'; this term originated in New Orleans in 1952 and was limited to the Deep South. Shortly thereafter, when it migrated to New England, it became known as the grinder, supposedly so named because eating this long sandwich required a lot of 'grinding' or chewing. Then, in 1954 in Connecticut, the sandwich was called the submarine, with reference its similarity to the shape of the boats built and housed in Groton, Connecticut. In 1955, the other names for this concoction- hero sandwich (New York City) and hoagie or hoagy (Philadelphia and New Jersey) - came into use. The use of 'hero' alludes to the heroic effort that was needed to eat the sandwich, but it is not known where the term hoagie came from. Submarine and sub are now widely used and not particular to a region. In Maine, they use both the terms Italian sandwich and sub. Sacramento, California joins New England in using the term grinder. In Miami, people use the name Cuban sandwich and the poor boy in New Orleans often features fried oysters. Other names for this sandwich are torpedo and zep (New Jersey), and wedge (downstate New York).

Source:
www.dictionary.com

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www.whatscookingamerica.net