These negatives had been labeled long ago as being either the Grand Review of the Armies or the inauguration of Ulysses S. Grant. Carol Johnson, a curator of photography at the Library of Congress, spotted the misidentification on Friday, Jan. 4, while checking old logbooks and finding the annotation "Lincoln?" in the margin. Only two other photos of Lincoln's second inauguration were previously known, but a careful visual comparison confirmed that these three negatives portray the same event.
"These negatives add to our knowledge of this special event," said Johnson. "They show what that wet Saturday looked like with the massing of the crowd. They also convey the excitement of the people."
Links to the other photos can be found here.