Abraham Lincoln photos are rare, especially those from the day of the Gettysburg Address.
For years only one such photo was thought to exist, but now that may not be the case.
"I think it's absolutely staggering to see something like this that was in a sense hidden in plain sight," said Lincoln author Harold Holzer.
Holzer thinks the image of a person in one of only two known photographs taken at Gettysburg on the day of Lincoln's address looks like Lincoln possibly arriving to the stage on horseback.
"To have the moment recorded minutes before he's about to give his greatest rhetorical triumph is very significant," said Holzer.
Last year a Hanover, Pennsylvania man found the photo.
It was on the Library of Congress' Web site all these years.
The Center for Civil War Photography enhanced it.
It has not been confirmed that the photo actually shows Lincoln.
Historians say one of Lincoln's good friends was at Gettysburg that day.
He was a tall, bearded man who wore a top hat as well.
The mystery has Lincoln scholars and enthusiasts buzzing.
"It's exciting my goodness. It took a long time to see that. So we're all going to decide whether that's really Lincoln or some copycat," said history buff Darla Moe,