The idea for a memorial to Lincoln began pretty much after he was assassinated in 1865. In 1867, Congress heeded these demands and formed a commission. Someone was chosed to create the monument but the idea died.
In 1910, a bill was passed for the creation of a new commission. In the end, the current design was selected and in 1922, the memorial was completed.
This very statue has been the scene of many movies, TV shows and video games. In an episode of the Simpsons, Lisa sets in motion the steps that would lead to the removal of a Congressman. In Fallout 3, one of the missions is to return Lincoln's head.