Top: Type I (75% silver) Middle: Type II (90% silver, lighter) Bottom: Cu-Ni I don't own a Type III yet, alas. I find the mid-1800s fascinating in US coinage because of the disruptions to the price of gold and silver due to the Gold Rush and then the Civil War. The 3-cent piece was introduced to match the denomination of the new 1851 prepaid postage stamp. It was also as a subsidiary coin with less silver content to replace the 90% silver coins which had been driven out of circulation by the relative rise in the price of silver caused by the Gold Rush. The Type II was needed to match the 7% debasement of the half dime, dime, quarter and half dollar of 1853 (the one which caused arrows to be added to the sides of the date). The fineness was raised to 90%, but the weight was dropped a bit, so that the 3-cent had move silver value than before and the other subsidiary coins had less, but at least they all matched. (The silver dollar was not debased in 1853, but those were not minted in large quantities in that era anyway.) The copper-nickel 3-cent was needed because of the Civil War, where unbacked "greenback" paper money drove precious metal coinage out of use. The bronze 2-cent piece and copper-nickel 5-cent piece (replacing the half dime) were introduced in that era for the same reason. The resumption of specie payments for greenbacks in the mid-1870s brought the dollar back up to par with gold and silver (while wrecking the economy in the Panic of 1873) and reduced the need for base-metal money. This contributed to the discontinuation of the 2 and 3-cent coins, though the nickel 5-cent piece is still with us.