Unless something changes soon, New Hampshire’s population will reach a peak in 18 years and then start to decline as the Baby Boomer generation dies off.

That’s one conclusion of a report by the Department of Business and Economic Affairs Office of Planning and Development. If current trends continue, it says, the state population will grow to 1.51 million in 2040, almost 10% above the current 1.38 million, before edging downward to 1.50 million by 2050.

The Office of Planning and Development issues population projections every five years. The projection is based on current rates of fertility, mortality and migration, according to Ken Gallager, principal planner with the office.

“The data is not a prediction of the state’s future population, but what is likely if the current factors transpire,” a press release stated.

New Hampshire has seen more deaths than births for a couple of years. The only reason the population is not already declining is that enough people are moving here, usually from other states.

“The main factor in the growth is migration,” Gallager said in the release. “Between 2020 and 2025, the state is projected to have a net in-migration of 51,600 and we anticipate that in-migration to be consistent – between 50,000 and 52,500 in each 5-year time period.”

After 2040, the project shows that this in-migration will not be able to compensate for an increasing discrepancy between births and deaths.