The Arithmetic of Decline
New Hampshire's population grew 7.5% over the past 15 years, but the state hasn't produced that growth itself. Since 2017, deaths have exceeded births every year, according to the New Hampshire Fiscal Policy Institute. The increase exists only because Massachusetts residents keep moving north, a dependency that transforms what looks like demographic health into a regional zero-sum game neither state can win.
The mechanism is straightforward. New Hampshire attracts Bay State transplants through lower housing costs and no income tax. Those migrants offset the natural population decline from an aging resident base. Remove the Massachusetts pipeline, and New Hampshire's population curve bends downward. The state isn't growing. It's being kept alive by its neighbor's overflow.
The Massachusetts Lifeline
Migration from Massachusetts dominates New Hampshire's population gains, data from Business NH Magazine shows. While the state has attracted some residents from Texas and California, those numbers represent statistical noise compared to the cross-border flow from the south. The pattern reveals something uncomfortable: two New England states competing for the same aging, shrinking population pool rather than addressing why neither can sustain itself organically.
Massachusetts faces its own demographic pressures, high housing costs, an aging population, and young families priced out of urban centers. When those families relocate to southern New Hampshire, they solve their immediate problem but create a regional dependency. New Hampshire's economic model now relies on Massachusetts generating enough population pressure to keep sending people north.
What happens when that pressure eases?
The Birth-Death Crossover
The 2017 crossover, when deaths began consistently outpacing births, marks the year New Hampshire's demographic model fundamentally changed. Before that point, migration supplemented natural population growth. After it, migration became the only source of growth. The New Hampshire Fiscal Policy Institute's data shows this isn't a temporary blip. The gap between births and deaths has widened each year since, driven by an aging population and declining fertility rates that mirror national trends.
New Hampshire's political leadership has largely treated Massachusetts migration as evidence of policy success, proof that low taxes and limited regulation attract residents, rather than as a temporary patch over demographic decline.
The Ponzi Scheme Problem
Ponzi schemes collapse when new investors stop arriving. New Hampshire's migration-dependent model faces a similar mathematics problem. The state needs Massachusetts to keep producing people willing to relocate, but Massachusetts itself struggles with the same aging demographics and below-replacement fertility. Both states are drawing from a regional population that peaked years ago and hasn't found a way to replenish itself.
The Expiration Date
Every migration-dependent model eventually hits its limit. For New Hampshire, that limit appears when Massachusetts either stems its outflow or runs out of young families to send.
Regional cooperation might offer an alternative, New England states jointly addressing the policies that drive demographic decline, from housing costs to childcare to immigration. But cooperation requires admitting the current model doesn't work. New Hampshire would need to acknowledge that its growth comes at Massachusetts' expense, and Massachusetts would need to confront why families keep leaving. Neither conversation has started in any serious way.
The 7.5% growth figure will appear in economic development materials and political speeches. It sounds like success. But the arithmetic underneath tells a different story: a state that hasn't grown on its own in nine years, sustained by a neighbor facing the same slow decline.