(CNN) -- In a nondescript office building steps away from the White House, a small team of librarians at the White House Historical Association is working on a massive puzzle.
As of this week, the group has now spent two years chipping away at digitizing approximately 25,000 previously uncatalogued slides of photographs documenting years of White House history.
"We wanted to be the authoritative source for White House history," said Lauren Cahill, the association's digital asset librarian, who says their mission is to educate and make the White House more accessible.
The project, they estimate, is about halfway done.
Most of the slides come with very little context or information, save for the month and year the film was developed. It's up to the librarians to identify what's in each photograph, which range from historical events to candid behind-the-scenes shots, and from the documentation of rooms from administration to administration to decor. The photos were taken between 1962 and 1987, the Kennedy through Reagan administrations.
So the librarians have become historical detectives of sorts — matching up what they know about the photo with other historical records and information. For instance, civil rights leaders in a photo from an April 1966 meeting with President Lyndon Johnson were identified using Johnson's daily diary, searchable through his presidential library. Some of the decorative pieces and artwork have been traced through old White House guidebooks.
It's an arduous process requiring a fine attention to detail.
Library director Stephanie Tuszynski travels one hour to Largo, Maryland, where the slides have been kept in cold storage for several years, carefully packs them into bags and drives them another hour to Creekside Digital in Glen Arm, Maryland, where the slides are scanned and digitized. Then, the librarians identify what's in the slide, captioning it with a background and narrative with as many details as possible. The librarians send batches of photos to the historian team for fact checking, then make revisions and a final review before the photos go live on the White House Historical Association's new online library. The digitization efforts are part of a partnership with Amazon Web Services, which provides cloud storage and support for the digitization.
Metadata librarian Leslie Calderone joked that she's fallen into rabbit holes with particularly challenging photos, but she's also starting to recognize people in photos throughout various administrations.
The photos also offer slices of White House life that aren't normally documented elsewhere and in most cases, have never been publicly accessible.
"These photos remind you it is a house, and people were being people here, setting the table, tidying rooms," said Alexandra Lane, the White House Historical Association's rights and reproductions manager.
The librarians found behind-the-scenes images of a visit from NASA astronauts that were part of the Gemini 4 team. President Lyndon Johnson presented the astronauts with the Exceptional Service Medal, but he also invited the astronauts and their families to take a dip in the White House pool while they stopped by for a Rose Garden ceremony. The images, which had never before been accessible to the public, show the esteemed astronauts splashing around the pool with their children, offering a more candid look at those who visit 1600 Pennsylvania Avenue.
Another set of images show the White House press corps in a West Wing press center in the Johnson administration. The reporters, mostly men, have cubby workspaces with telephones, and there are three televisions in the room, all of which are turned off. Another image of the "press lobby" inside the west wing shows reporters kicked back on leather chairs, ashtrays on each table. The dedicated press space used today was built above the White House swimming pool during the Nixon administration.
Another hidden gem: First lady Jacqueline Kennedy surprised a tour group visiting the White House. She greeted the group and posed for a photo on the North Portico.
™ & © 2018 Cable News Network, Inc., a Time Warner Company. All rights reserved.