Answer: Trapping

If you ever pondered how the slang for a U.S. dollar, a “buck”, is related to the word we use for male deer, you’ll be pleased to see just how on track you were with that line of thinking. Unlike many words where the etymology is murky at best or entirely unknowable, the etymology of buck as a slang term is clear cut.

Early on in American history, before there was even a United States let alone the modern dollar, early settlers, fur traders, and trappers were using the full skin of a buck as a unit of currency. As early as the 17th century, there are examples of people referring to purchasing power in terms of “bucks”, as in “two bucks for a wool blanket” or two buck skins in barter for the product.

Later on in the 19th century, the value of a single buck skin became fixed to the value of a U.S. dollar. In 1851, historian Henry Howe recorded the exchange rate of skins in the trapping trade:

A muskrat skin was equal to a quarter of a dollar; a raccoon skin, a third of a dollar; a doe skin, half a dollar, and a buck skin, “the almighty dollar.”

While the other terms never caught on—no child standing in a 1950s soda shop ever exclaimed, “A whole muskrat for a bag of licorice! What a rip off!”—the use of the term buck in place of dollar certainly did, and long after people were trading male deer pelts for goods and services, the slang lives on.