The half dime was a silver coin, valued at five cents, formerly minted in the United States.
The denomination was one of the original coins first authorized in 1792, and production began the following year. These coins were much smaller than dimes, in diameter and thickness, appearing to be "half dimes".
In the 1860s, powerful nickel interests successfully lobbied for the creation of new coins, which would be made of a copper-nickel alloy; production of such coins began in 1865 and were struck in two denominations — three cents and five cents (the latter debuting in 1866).
The introduction of the copper-nickel five-cent pieces rendered the silver coins of the same denomination redundant, and they were discontinued in 1873.
The following types of half dimes were produced by the US Mint:
Flowing Hair Half Disme (sic) Pattern, 1792
Flowing Hair Half Dime, 1794-1795
Draped Bust Half Dime (Small Eagle Reverse), 1796-1797
Draped Bust Half Dime (Heraldic Eagle Reverse), 1800-1805
Capped Bust Half Dime, 1829-1837
Seated Liberty Half Dime (various subtypes), 1837-1873
Canada also once used silver coins of five-cent denomination; they were colloquially referred to as "fish scales," due to the fact that they were very thin (the term "half dime" never having been used in Canada), and were produced until Canada also switched to nickel five-cent pieces in 1922. Only a very small number of the silver five-cent coins were minted in the final year of production in 1921, and these coins rank among the rarest in the annals of Canadian numismatics.