The United States Small Cents
In 1857, congress passed an act reforming the way minting of the copper coinage of the United States. Due to the expense of minting both half cents and large cents, it was decided that henceforth all minting of half cents was discontinued and the new cents were to be of a much smaller size. In fact, it was said that both earlier coins were unpopular outside of large cities and the new, smaller coin was soon in widespread use to the satisfaction of all.

Flying Eagle Cent - 1856 to 1858
Indian Head Cent - 1859 to 1909
Lincoln Head Cent - 1909 to current