A statistician at the Bureau of Standards was single-handedly the Google Streetview of mid-century Washington, D.C.

After moving to D.C. from California, John Wymer made a map that subdivides the city into 57 sections and went out in his spare time to photograph city blocks, churches, schools, and other notable buildings. Between 1948 and 1952, he built up a trove of 4,000 photographs that is now treasured by researchers for its unvarnished view of everyday life in D.C.

“It’s not just pictures of monuments and memorials. It’s houses and churches and how people were living their lives,” says Jessica Smith, who has taken about half those images so far and paired them with their modern equivalents: Google Streetview snapshots.

The result is Wymer’s DC, an interactive map that juxtaposes quotidian life of then and now on a split-screen.

The satistician’s personal project “was always described to me as his way of getting to know this new city that he lived in,” Smith says. He gifted the cache to the Washington Historical Society in 1978, and it has become one of the society’s most frequently used collections.

In a sense, Smith has followed directly in the photographer’s footsteps. She moved here in 2014 to complete a master’s degree at George Washington University. As an intern at the Washington Historical Society, she came across the Wymer collection, which is remarkable in several different ways. In addition to focusing on sites and parts of the city that other photographers overlooked, he undertook the project in a very methodical way, going section by section and providing geographical notes.

“One day it kind of clicked that someone should map it, and how great would that be. At the time I didn’t think it would be me,” says Smith, who is now a librarian at the Historical Society.

She wound up undertaking the massive project, in partnership with her software engineer husband, as a case study for her master’s thesis, which advocates for making such collections more accessible and relatable to the public.

Wymer’s photographs are among hundreds of thousands in the Washington Historical Society collection, but they aren’t necessarily approachable for non-researchers.

“These images do exist in the catalog, but you have to be able to find them, and then you’re looking at them as a single image,” Smith says. “What I did was place them in a way that people could relate to.”

It’s time-consuming work. She estimates it takes about three hours to upload and place 100 images—if she’s careful not to fall down any rabbit holes when an image’s location isn’t easily identifiable. Currently, there are 1,900 photographs up on the site.

Smith’s hope is to finish her own project around the spring, though it is partially contingent on when the Washington Historical Society finishes digitizing the remaining 2,000 Wymer photographs (the non-profit recently raised funds specifically to continue work digitizing its extensive collection). The project is independent of the Historical Society, but Smith says they have been an invaluable partner in supporting her work and granting usage rights to the photographs.

While Wymer’s primary objective was showing the city’s architecture, Smith says she particularly treasures the photographs that show people in them. One of the map’s filters allows viewers to specifically see scenes with people in the foreground—kids playing stickball in a street now filled with cars, a group of men playing basketball where a playground now sits, people coming out of churches that often still exist.

“It’s both interesting to see the things that have changed and the things that haven’t changed,” Smith says, noting that the old photos also show a downtown filled with smaller buildings and historic character that have often been replaced with huge, monolithic buildings.

“I think I’m really annoying to travel with these days. My friends are like ‘We get it Jessica, you know where buildings used to be,'” Smith says. “I just love knowing this much about D.C.”

See more at Wymer’s DC