Contrary to popular lore, Lincoln did not write the Gettysburg Address on the back of an envelope. Though given short notice that he was to speak at the dedication of the Soldiers’ National Cemetery, he had enough time to write two drafts of the address prior to November 19th, 1863. These he entrusted to his private secretaries, John Nicolay and John Hay. The remaining three drafts were written well after the delivery of the address for inclusion in various charitable anthologies. Each draft differs slightly in wording and punctuation, most likely because each was written from memory.
This Sophie book compares the differences in the five drafts visually, provides information about the provenance of each draft, and features a reading of the address by Johnny Cash.
You can download it here. (.zip, 2.9 Mb) Make sure that you have Sophie or Sophie Reader installed.

By clicking on the title of the draft at the top of the text, the differences in wording will be highlighted, and information about the particular draft is displayed.