A screengrab of Prof. Matthew Pinker's online exhibit of the Gettysburg Address, and how it evolved. (Courtesy of the Google Cultural Institute/Courtesy of the Google Cultural Institute)

You can quote its opening line. You can probably quote its conclusion. You may even know that the famous speech, as delivered by President Abraham Lincoln 150 years ago, lasted only about two minutes.

But how much do you really know about the Gettysburg Address?

Despite the legend that the famous speech was scrawled on the back of an envelope on the train to Gettysburg, a new project from Google’s Cultural Institute presents five drafts of the discourse in Lincoln’s handwriting that show how it evolved into the version that schoolchildren across the country have committed to memory today.

Three of the versions featured in the Google project were written after the speech itself, but historians are divided on which of the remaining two accompanied Lincoln to the battlefield that day.

“We don’t know which he used when he delivered it,” said Matthew Pinsker, a history professor at Dickinson College who specializes in Civil War history and directs the college’s House Divided Project.

The White House, Library of Congress, Cornell University and the Abraham Lincoln Presidential Library and Museum submitted copies from their collectionsto the Google institute, which showcases online versions of art and archival documents. Pinsker, as well as historians from Cornell and the Lincoln Library, have also created online exhibits to add context to their documents.

Different accounts indicate different copies of the speech may have been used, Pinsker said. Eyewitnesses say that Lincoln pulled the speech from his coat — indicating that a copy with a fold in it may have been the one delivered 150 years ago. Another version bears speaking notes. There is also debate about whether Lincoln said the phrase “under God,” which appeared in later copies of the speech produced for charity, but may have been an impromptu addition from the lectern.

Information from the larger project, Pinsker said, is woven into an open online course the Dickinson College is offering on how Lincoln developed the phrase “a new birth of freedom.” The line — crucial to the speech’s closing — may have been inspired by New York Times correspondent Samuel Wilkeson’s dispatch about the battle. That report included news that his own son, Bayard, lay among the dead.

“This is the kind of story that nobody in the general public really knows,” Pinsker said. “We’ve put it together in a unique way, and it’s our most important new contribution.”

Other institutions involved in the project are celebrating in their own ways. Piotr Adamczyk, program director at the Google institute, said that the Lincoln library, for example, is having notable people, including former President Jimmy Carter and retired Supreme Court Justice Sandra Day O’Connor, write their own 272-word response to the famously short speech.

Adamczyk said he’s happy to give the drafts a “broader audience, and let them act together to tell that story.”