The shield nickel gets its origin in 1866 , just after the civil war in the US. It was the first US coin made from a nickel-copper alloy composition. Some say the genesis came from 1) the hoarding of silver-based half dimes during the civil war, 2) the desire by the US mint to start introducing non-precious metal based coinage, and 3) the nickel lobby led by Joseph Wharton. Regardless, the shield nickel was produced up until 1883 (business strikes) and 1886 (proof strikes). It is a collectible series, and this overdate example is a fan favorite, and especially tough in higher grades such as this proof 67. For the uninitiated, proofs are manufactured differently than regular, business strike coins. They are produced on specially prepared planchets and use a highly polished die with multiple strikes to finish the near perfect rendering of the design. Proofs are almost always extremely low mintage as they were (and are today) made for collectors of numismatics, and not for circulation.
