In 2009, the U.S. Mint made four special penny designs to celebrate Abraham Lincoln’s 200th birthday. It was also the 100th anniversary of the Lincoln penny, which the Mint first made in 1909. The image of Lincoln remained on the obverse (heads) of all four cents in the new program. The reverse (tails) included four different designs from important phases of Lincoln’s life, from his birth all the way to when he was president.
After the program ended, the reverse of the penny changed to the current "Union Shield" design. It represents the unity of the states, which President Lincoln worked so hard to restore and preserve.
To learn more about these pennies, visit the Lincoln Bicentennial One Cent Program page on the U.S. Mint website.