D.C. Mayor Muriel Bowser. (Andrew Harnik/For The Washington Post)

The elected leaders of the District and Montgomery and Prince George’s counties signed a first-of-its kind agreement Tuesday to develop a joint strategy for ending homelessness.

None of the three Democrats — D.C. Mayor Muriel E. Bowser, Prince George’s County Executive Rushern L. Baker III and Montgomery County Executive Isiah Leggett — claimed to have the solution to a problem that afflicts an estimated 12,000 people across the Washington region.

But they emphasized that homelessness recognizes no jurisdictional boundaries and that homeless families and individuals often migrate, looking for what they believe may be the largest helping hand. Until the three governments learn to operate in a more concerted fashion, the officials said, the problem will persist.

“It’s vitally important that we have a regional approach,” said Bowser, who has released the city’s own plan to end homelessness there within five years. Among her objectives is replacing the notoriously dilapidated family homeless shelter at the former D.C. General Hospital and leasing and building smaller-scale facilities.

The three area officials believe that their jurisdictions can be more effective by sharing casework information and tracking homeless people with more cohesion. Another goal is sharing more information about available housing and employment opportunities.

“Step One is getting us all in the room together and having an honest conversation about who we are serving and not serving,” said Prince George’s Social Services Director Gloria Brown, one of several top officials from each government who attended the signing ceremony at a homeless shelter in Silver Spring.

Although homelessness decreased by almost 4 percent nationally between 2012 and 2013, it increased by 3.5 percent during that period in the Washington region.

The scope and urgency of the District’s situation far surpasses those of Prince George’s and Montgomery. About 65 percent of the area’s homeless — some 7,748 people — are within in the District’s borders, far more than the 891 homeless people known to be staying in Montgomery or the 654 in Prince George’s.

Different jurisdictions also operate under a somewhat different set of policies and rules. Homeless people in the District have a legal right to shelter during hypothermia season, for example. In Montgomery, however, those who became homeless in other jurisdictions will be fed but are not entitled to shelter.

But those at Tuesday’s regional summit agreed that the underlying causes of homelessness are the same — the most critical being the lack of affordable housing throughout the region.

Rental costs in the Washington area are about 169 percent of the national average, second only to San Francisco-Oakland among metropolitan areas.

A “Charter to End Homelessness” that was signed by Bowser, Baker and Leggett created a regional coordinating council that will meet regularly and work to align their efforts more effectively. “It starts the dialogue,” Leggett said. “ It raises this issue to the top of the list.”

The signing also reflected the affinities between the three African American leaders, whose lives and careers have intersected at various points. Baker, a law student of Leggett’s at Howard University, worked with the homeless as a young lawyer with the District’s Department of Housing and Community Development. One of Bowser’s early jobs in Montgomery government was as assistant director of the Silver Spring Regional Center. It was Bowser who pitched the idea of a joint approach during a breakfast with Leggett at the Parkway Deli in Silver Spring in January.

Tuesday’s summit was held at Progress Place, an aging Silver Spring homeless facility that will soon be replaced by a building on Georgia Avenue. Washington Property Co., a private developer, agreed to build a new facility in exchange for several parcels of land for high-end apartments. The new building will have three floors of medical and social services for the homeless and a fourth floor with 14 personal living quarters.

Bowser looked at the plans for the project and said they were similar to what the District has in mind, replacing such shelters as the one at D.C. General with smaller-scale, more humane facilities. “We’re going to need about eight of those,” she said, “and they’re going to be in somebody’s neighborhood.”

Baker echoed that theme, noting that citizens everywhere have a collective responsibility to receive the homeless as their neighbors. “They’re ours,” he said. “We all belong to each other. We can’t ride without taking everybody with us.”