Why is the edition of penny from 2009 unique?

Among all 2009 Penny version stands out because it contains four variations of reverse designs which commemorated Abraham Lincoln's 200th birth anniversary. The reverse designs of 2009 pennies depict essential periods in Lincoln's existence starting from Birth and Early Childhood up to Formative Years, Professional Life and Presidency. Some 2009 pennies received a composition modification by being produced in copper alloy. All face value pennies hold their value but value increases for uncirculated and high-grade and error versions that collectors seek. These coins remain popular with numismatists since they possess important historical value.