BOSTON - The state's population is growing at more than double the rate of other Northeastern states, but that growth is expected to slow as the baby-boom generation enters its golden years.
An aging state creates myriad policy challenges for state and local officials, who are stretching to balance the demands of older residents while attracting new business and younger families.
Overall the North of Boston region is expected to grow by more than 6 percent by 2035, though some cities and towns will see their populations shrink dramatically, according to a recent study by the Donahue Institute, a policy research center at the University of Massachusetts.
Essex County's population will swell to 831,063 while Middlesex -the state’s most populous county — will grow to nearly 1.7 million over the next 20 years, the report projects.
Massachusetts' population will rise 8 percent to more than 7.3 million, the report suggests.
While many communities — including Lawrence, Lynn, Beverly, Andover and North Andover -- will continue to grow, the study's authors expect that others that skew older — such as Gloucester, Marblehead, Rockport and Hamilton -- will see populations wither.
"Over the long term, a community’s age structure is a large determinant of its fate," said Susan Strate, a program manager at the Donahue Institute and co-author of the study. "So a city or town that is predominately populated by baby boomers will start to lose population rapidly after 2030."
That's the case with Newburyport, she said, where the 50 to 54-year-olds were the dominant age group in 2010, when the last nationwide count was taken.
The city is projected to shed more than 5 percent of its population by 2035, from 18,054 to 17,221 residents, the report predicts.
Lawrence - among the state's youngest communities with nearly 40 percent of its residents under 18 as of 2010 - is expected to grow 14 percent to 94,291 in the next two decades.
Strate said the projections are based on census figures, migration trends and fertility rates. They don't account for new housing, investment or other factors that could reverse the decline - or slow the growth – of some communities.
For the most part Massachusetts' population has steadily climbed. With a population of more than 6.7 million in July 2014, according to recent U.S. Census estimates, Massachusetts held onto its spot as 14th most-populous state in the nation.
Locally Essex County is growing slightly faster than the state, or roughly 0.7 percent from 2013 to 2014. The region's population was 769,091, according to U.S. Census estimates.
Strate said Massachusetts is no boom state but is swelling faster than New Hampshire, Maine, Vermont and others in the Northeast.
International immigration fuels much of the growth, she said.
Among the report's other key findings:
* The state's population aged 65 and over will almost double in 20 years and increase from 14 percent to 23 percent of the total.
* The population aged 19 and under is expected to decrease. It will fall from 25 percent of the overall population to just 21 percent.
Mike Festa, state director for the Massachusetts chapter of the American Association of Retired Persons, said an aging population is pushing officials to improve access to senior housing, healthcare, transportation, as well as recreational opportunities.
The AARP is working with state and local governments to create "age-friendly communities" as baby boomers age and their needs change, he said.
Festa called baby boomers a "major driver" of the economy and said they shouldn't be viewed as a drain on healthcare and other services.
"Many of them are working beyond retirement and are in their highest earning years. They're spending that money in the state's economy," he said.
But local governments are straining to accommodate the needs of baby boomers while also turning to younger generations.
Erin Battistelli, a Rockport selectman, said the town's shrinkage is a wake-up call for local officials who are discussing a host of new initiatives to attract younger families to settle down on Cape Ann.
"We welcome people who want to retire in our community, but we're very concerned about this trend," she said.
Rockport, which lost 10 percent of its population from 2000 to 2010, according to the U.S. Census figures, is projected to shed another 32 percent of its residents by 2035, dropping its population to 4,523, according to the UMass study.
In Methuen, where the population is projected to rise 21 percent, Mayor Stephen Zanni is embracing the growth by trying to attract new housing development and businesses that create jobs.
The town is growing slowly, he said, which blunts the added burden on schools and municipal services.
"We're trying to do it in a way that doesn't have a major impact on schools and traffic congestion," he said.
Hamilton, which is projected to shrink 32 percent by 2035, hopes to "stem the tide" of a declining town by providing more housing options for younger professionals, said Town Manager Michael Lombardo.
The town is overhauling its schools and has added recreational amenities to attract new families -- a new playground at Patton Park and a community pool.
"It's a balance," Lombardo said. "We certainly embrace our senior populations and want to create a community where they can age in place, but we really need to focus the other end of that spectrum.”