An abandoned parking lot in Harlem and a former airport in Flushing may not appear to have much in common besides weeds, but for the volunteers of 596 Acres, these are the next frontiers of a civic movement to reclaim public space in the city.

The group’s name was inspired by the total area of vacant, city-owned land in Brooklyn, where the project’s founding members live. Over the past year, they have worked with local residents in Bedford-Stuyvesant, Greenpoint and Gowanus to reclaim four vacant lots owned by the city Department of Housing Preservation and Development (HPD) as community gardens and gathering spaces. Now the group is expanding its horizons into Queens and Manhattan, starting with a “visioning session” this Saturday afternoon in the East Village.

Co-founder Paula Z. Segal, who works as a law clerk by day, calculates that 75 city-owned lots in Manhattan and more 100 in Queens are ripe to put back into public use. She started out two years ago simply trying to find out what she could do to revive a single vacant lot. Her persistence took her to the city’s department of Citywide Administrative Services, where she found she could get information on the ownership not only about her lot but also hundreds of others around the city.

“I couldn’t keep that information to myself once I had it,” said Segal.

Working with computer programmer Eric Brelsford and other volunteers, she compiled detailed information on the location and government agency ownership of every vacant city-owned in her borough — and then turned it into an interactive map.

That map has been a powerful organizing tool for the group, which also holds neighborhood planning sessions advising residents how to approach city agencies to seek permission for temporary use of the property. To spark the interest of passersby, the group tags empty lots with signs encouraging neighbors to seek to reclaim them.

The data-sharing has supercharged the New York tradition of organizing neighborhood residents to reuse empty city-owned land as community gardens. Nearly 200 gardens citywide now have permanent protection. Most were created in in the 1970s and 1980s, when the city owned massive amounts of abandoned private property.

The city has a much smaller number of parcels now. The name 596 Acres is a bit of a misnomer; as Segal and others later discovered, many sites were in fact occupied. Some were stalled construction projects. Others turned out to be community gardens the city hadn’t classifed properly. As volunteers refine the information, they update their map to show only the spots that offer genuine opportunities.

Graphic designer Alison Iven volunteers at one of the most recently added sites, on Patchen Ave. in Bed-Stuy. (“This is a great little lot, I’d be happy to help get this going,” she posted on the map.) She said it took just six weeks to file the appropriate paperwork to HPD and get permission to start work. So far, she and other volunteers have been clearing rubble from old construction. But eventually they envision a garden with playground equipment for children, called Patchen Community Square.

“There are not a lot of safe spaces here that are green and close,” she said.

Before Patchen Community Square can emerge, volunteers must clean the city-owned lot. Photo: Alison Iven

Queens native Helen Ho works with many neighborhood-based environmental projects as community outreach and project support manager for IOBY, which stands for “In our backyards” and functions like a Kickstarter for community environmental projects. Patchen Community Square and other 596 Acres gardens are raising money there now for supplies. So is 596 Acres. When Segal came last year looking to raise $300 to print posters mapping every city-owned lot in Brooklyn, her project jumped out at Ho for its innovation and ambition. Ho is now helping 596 Acres build alliances with Queens residents, starting with a workshop next Wednesday.

“This isn’t just looking at one space,” Ho said. “This is looking at transforming the way the city looks at all of its spaces.”