Kathleen Weiss, 61, of Arlington and Wade Crump, 52, of Ellicott City, Md., map a block of the Shaw neighborhood. (Mary Hui/The Washington Post)

After the storm clouds had passed on a recent summer evening, about 20 people, armed with smartphones, pens and clipboards, fanned out in teams of two to three in the District’s Shaw neighborhood to conduct street surveys.

Each team’s mission: to map a city block.

These citizen cartographers are members of Maptime DC, a group founded in 2014 with the aim of democratizing the field of digital mapping. Run by volunteers, the group regularly hosts sessions where members can learn the basics of mapping software, web platforms and mapping techniques.

The D.C. area is home to several such groups, including MappingDC and Geo DC. These three groups alone boast more than 3,000 members. Together, members meet up to discuss developments in cartography and conduct street surveys across the city to improve neighborhood maps.

The work is “sort of a public service, if you will” said Steven Johnson, 60, a geospatial professional active in the mapping community. He is a co-organizer at Maptime DC and MappingDC and also leads TeachOSM, an online resource designed to introduce teachers and students to OpenStreetMap, a free and open Web map of the world.

Kathleen Weiss uses the Pushpin app to map a block. (Mary Hui/The Washington Post)

Visually, OpenStreetMap is similar to Google Maps; the key difference is that anyone can edit it. If Google Maps were Encyclopedia Britannica, then OpenStreetMap would be Wikipedia.

The fact that anyone can add to the map, Johnson said, is “tremendously empowering” and its value to the world “almost inestimable.”

After the Haiti earthquake in 2010, for example, hundreds of volunteers around the world collaborated to produce a crowdsourced crisis map. They used satellite imagery to trace the road network onto the country’s OpenStreetMap and also mapped eyewitness accounts sent via text messages, emails and Twitter, aggregating incidents to give disaster-relief workers a better sense of the patterns of destruction. And in 2015, after a massive earthquake crippled Nepal, volunteers again took to OpenStreetMap to map areas of massive destruction, helping to coordinate and direct aid to the hardest-hit regions.

In day-to-day life, free and open mapping also means that there is no need to wait for official cartographers. All one has to do is pull up OpenStreetMap and start editing. One might add the neighborhood Bikeshare station or a recently opened business, or note interesting architectural features of buildings.

These are hyper-local neighborhood elements that are important to the daily lives of real people but that official cartographers do not have time for, Johnson explained.

That is where volunteer cartographers come in. In the past two years, for example, members of MappingDC have charted neighborhoods including Columbia Heights, Petworth, Minnesota Avenue and the Atlas district, and Old Town Alexandria.

Mappers have also partnered with the government. In late 2014, MappingDC began a collaboration with the District’s Great Streets commercial revitalization program. Volunteers met for regular “mapping parties” in the emerging commercial corridors identified by the government, gathering, uploading and editing data about local businesses in OpenStreetMap.

Wade Crump studies a Field Papers printout of the block he needs to map. (Mary Hui/The Washington Post)

On their recent Tuesday evening meet-up, Maptime DC members used three mapping tools on their street survey of Shaw. Some used a tool called Field Papers, which allows users to print a map of a selected area, write and draw on it while in the field and then digitize and upload the drawing by taking a photo of it. Others used an app called Pushpin, which allows volunteers to edit and add data to OpenStreetMap. Still others used an app called Mapillary, a Swedish start-up that uses photos to create a crowdsourced version of Google Street View.

“We try to instill in everyone that all parts of the map are created equal,” said Johnson, who works as a geospatial project manager. “All those sexy places have been mapped and mapped again,” but what he wants to do is give visibility on a map to otherwise marginalized groups, he said.

Mapping a neighborhood’s transformation

Shaw has undergone tremendous change in recent years, and that is exactly why Maptime DC chose it for the group’s inaugural fieldwork session, said Andrew Wiseman, 36, another co-organizer and a part-time geography professor at George Washington University.

“There are a lot of new businesses, a lot of change in this area,” said Wiseman, who wants to see those changes documented and mapped.

And so the mappers set off to do just that.

Kathleen Weiss, 61, a performance consultant from Arlington who is new to mapping, paired up with Wade Crump, 52, a senior geographic information systems analyst and veteran cartographer from Ellicott City, Md. They were to map the 800 block of R Street NW, a residential area two blocks from the Shaw Metro station.

Crump had decided to use Field Papers, and as he walked down Ninth Street NW, he jotted notes in pencil on his printout of the block. He also had a GoPro camera attached to the strap of his sling bag, which snapped photos automatically every few seconds, which he would later edit and upload to a crowdsourced street-view map.

Weiss, meanwhile, had chosen to use the Pushpin app on her iPhone. As the mapping duo walked by a brown brick building, they stopped to document its attributes. Weiss found the corresponding building on her iPhone, dropped a pin on it and started typing details. She noted that it was a three-story apartment building, No. 807. On one side of the building hung a large banner that read, “Heritage at Shaw Station. Now leasing luxury apartment homes.” Crump scribbled down the name.

These brown brick buildings tell the tale of a changing neighborhood. Until 2013, they were part of the Lincoln Westmoreland housing complex, which participated in the federal Section 8 program, enabling low-income residents to live there.

In 2013, however, Lincoln Westmoreland transformed into “luxury apartment homes,” as the banner advertised. The buildings look the same as before. The only change was that the landlords opted out of the Section 8 program, put their units on the market at market rate and repackaged them as “luxury apartment homes.”

For the next half hour, Weiss and Crump continued mapping the city block with exacting detail. Crump even made note of a green fire hydrant on the corner of Ninth and R streets NW, and Weiss noted a surveillance camera on Eighth Street.

Soon, however, the half hour was up, and it was time to reconvene with the group.

“It’s very easy to get obsessed,” Crump said.

Beyond data

Back at their meeting spot in the lounge at the WeWork Wonder Bread Factory, group members huddled around laptops. Over slices of pizza, they pulled up OpenStreetMap and began to enter their newly collected data.

It is time-consuming work. So why do all these mappers bother to do this on top of their day jobs?

For Crump, it is a mix of personal satisfaction, civic pride and helping the greater good. He said he likes being able to see the best possible map of his city and being able to say, “Here’s my city, it looks great, and I’ve done a lot of work.”

Crump also sees it as a hobby, but it goes beyond personal recreation: “I’m out, getting exercise, using my brain and helping the greater good in a way.”

Weiss said she is drawn to mapping because of its potential to affect policy. “It’s up to the citizens to be the eyes and ears for local officials,” she said, and she wants to use maps and demographic data to tell a story that might, one day, inform the decisions of policymakers.

And for Wiseman, the co-organizer, community mapping opens up all sorts of new questions. Does a particular area lack certain city services? What kind of resources are available in this neighborhood? Which businesses have surveillance cameras installed, and which do not?

“It’s sort of open-ended. Once you have the data, you can really do anything,” Wiseman said.