The smallest denomination coin ever circulated in the United States was valued at five milles, equivalent to one 200th of a dollar. This half-cent coin was minted for 65 years, from 1792 until 1857. It was made entirely of copper, and featured the head of Lady Liberty on the obverse and “half cent” surrounded by a wreath on the reverse. Despite their low value, these coins were relatively physically large, only slightly smaller than a modern U.S. quarter.
The half-cent coin was discontinued by the Coinage Act of 1857, but at the time it was eliminated it still had more buying power than a present-day U.S. dime—due to inflation, a half-cent in 1857 was worth about 15 cents in modern dollars. Therefore if the United States government was consistent in eliminating coins when they fell below a certain spending-power threshold, the lowest value U.S. coin being minted today would be the quarter.