Washington (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.

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