A draft of the plan, called Imagine Boston 2030 envisions new neighborhoods emerging from underdeveloped pockets of a city that is bursting at the seams in more central locations. Walsh officials said they will use the master plan to sustain and redirect growth more evenly around the city, and to attack seemingly-intractable challenges, from pricey housing, to traffic-choked streets, to rising sea levels.

Boston’s building boom will need to stretch into some of the farthest reaches of the city to keep pace with a population that could hit 800,000 by 2050, according to a new citywide master plan the Walsh administration previewed Thursday.


Mayor Martin J. Walsh noted that the last big master plan developed for Boston was in the 1950s.

“The result of that plan was a thriving city,” Walsh said. “This city’s going to be very different as we move forward from here. We want to make sure as we grow and change, that we grow for everyone.”

One key element of the 300-page document is “expanding neighborhoods,” in which a half-dozen pockets, mostly on the outer edges of the city, would be targeted for large-scale mixed-use development. Many of these locations already have good access to public transit, city officials point out, and have lower land costs to allow for more moderately-priced housing. That would help relieve pressure on more popular neighborhoods where prices have soared.

Among the areas targeted for additional development are Suffolk Downs, Sullivan Square in Charlestown, the Beacon Yards in Allston, and Readville in Hyde Park.

“These are places where you can imagine transformational change,” said Imagine Boston 2030 director Rebekah Emanuel.

Two other areas singled out in the report are already in the crosshairs of development: the Widett Circle industrial yard off Interstate 93 and the “100 acres” section of Fort Point, where General Electric Co. is soon to build a new headquarters.


Elsewhere, though, the city’s development agency recently approved a 177-unit apartment building at the Hood Park complex in Sullivan Square. And earlier this week, developer Jordan Warshaw filed plans for a 521-unit apartment complex near the commuter rail station in Readville.

Warshaw is a veteran of the downtown luxury market, but said there is a big opportunity building middle-class housing in outer neighborhoods.

“This is the kind of project that can really transform this city into a place where middle-income people can afford to live,” Warshaw said in an interview earlier this week. “You’re not going to solve that 80 or 100 units at a time. You’ve got to think big.”

Boston is already on track to add at least 40,000 housing units this decade, said Walsh’s housing chief, Sheila Dillon, a 15 percent increase from 2010. But if the city’s population grows as projected, Boston will have 800,000 residents by 2050, up from around 656,000 today. That would match Boston’s all-time high in 1950.

Housing those new people will require another 50,000 units, according to the master plan, which will help determine where those homes get built.

“This identifies ways to be even more intentional about our growth,” Dillon said. “That could make a whole lot of difference.”

But any large-scale growth in this old and crowded city is going to require more investment in streets, sewers, transportation, and other infrastructure. The Walsh report even contemplates “nature-based and hard-engineered flood defenses” to protect low-lying areas from rising seas. Yet it gives few details on how to pay for all this.


Boston could tap private sector sources. Sara Myerson, director of planning for the Boston Planning & Development Agency, said the city could explore joint ventures with private investors, and induce developers to pay for street work and parks around their projects. They’ll also look to Washington and Beacon Hill for help.

No matter how they’re paid for, those sort of improvements are long overdue, Walsh said.

“If we want to be competitive on a global scale, on a national scale, we’d better start investing in infrastructure,” he said. “We’re talking about decades of neglect.”

Imagine Boston has other ambitions: reducing greenhouse gas emissions; improving service on the Fairmount Corridor commuter rail line to better link some of Boston’s poorest neighborhoods to job centers; and completing the Emerald Necklace from Franklin Park to the waterfront.

The Walsh administration has held dozens of community meetings over the past year soliciting input for Imagine Boston 2030.

The draft version will be refined based on additional feedback and a final report is expected to be released in the spring.

Tim Logan can be reached at tim.logan@globe.com. Follow him on Twitter at @bytimlogan.