Head north on Rt. 95 and just before the border with Maine, high up on the Piscataqua River Bridge, there’s a bird’s-eye-view of Portsmouth, New Hampshire. It’s postcard perfect New England: a compact city of red brick and cobblestone built, for good reason, along the water.

“The settlers who came here had to settle on the coast. They needed water for transportation, they needed water for a food source,” said Rodney Rowland, director of facilities and special projects for Portsmouth’s Strawbery Banke Museum. “The oldest parts of our country are right on the water.”

Managing water has become Rowland’s priority. Strawbery Banke Museum is a carefully preserved neighborhood made up of dozens of colonial-era homes. It's located just across the street from the river. Many of the buildings have withstood two centuries of storms, but over the past decade they’ve been subjected to something new: record high tides.

“We’re seeing bigger and bigger storms,” said Rowland, “that are pushing the water farther and farther and harder and harder.”

Indeed,researchfrom the University of New Hampshire shows that over the next century, storm surges threaten to wipe out 14 percent of historic sites along New Hampshire’s seacoast. And this looming loss, experts say, isn’t just academic. It’s also about the bottom line — a potential downfall of tourism.

Among the hardest-hit homes in Strawbery Banke is a two-story colonial built in 1795.

“We’ve measured from 16 inches of salt water in this basement during periods of astronomical high tide to 26 inches of salt water in this basement during a nor’easter,” Rowland said.

Green mold has grown on the walls. A constant dampness has rotted mortar around the chimney bases and wood beams that support the house. Rowland fears it’s in danger of eventually collapsing.

“A couple of years ago one of the timbers holding up the first floor let go due to rot, and the first floor dropped a couple of inches,” he said. “We have a sump pump, [but] it doesn’t have a prayer of keeping up. It’s like pumping out the river.”

Some of the Strawbery Banke houses have been retro-fitted for flooding, but in at least one case, it meant sacrificing an original fireplace to make way for a concrete basement floor and drainage system. Adaptations aren’t perfect and they’re not cheap, but it could be worse. Other parts of the country, including Florida and New Orleans, have been hit by far more damaging floods. Even along New Hampshire’s 18-mile stretch of coastline, there are signs that history is already washing away.

“I feel oftentimes like I’m 20 years too late,” said Meghan Howey, an anthropological archaeologist at the University of New Hampshire who authored the 2018 UNH study.

Just outside Portsmouth on the banks of the Oyster River, Howey has uncovered the remains of one of New England’s earliest British colonies. Roughly built log Garrison homes dotted the river in the 1600’s. The remains of one of them is little more than a mound of dirt on the edge of a jagged river embankment.

An aerial photo analysis, she said, indicates the embankment’s erosion has been recent, likely over the past 20 years. A scattering of large rocks on an otherwise sandy shoreline is all that’s left of the home’s foundation.

“It’s gone, it’s fallen right out of the bank,” she said. “If the erosion keeps happening, there’s going to be more and more history that’s going to wash away before we can even get to it.”

She’s in a race against time — and rising tides — to locate similar sites along this river.

Rich in fish, timber and fur, the Oyster River was both the edge of wilderness and the heart of a 17th century global economy, Howey said. In the remains of Garrison homes, she’s found evidence of that era’s wealth: imported German mugs and French gun flint.

But even as she unearths the river’s history, Howey is worried about what the future holds for tourism in the area.

“I like to say the past is one of the biggest tourist destinations out there," said Howey. "If we have to move everything inland, is that going to still be perceived an authentic? Will people find other areas to go as tourists? And will the revenue sink, especially in areas like this?"

It’s a question for tourist destinations along coastlines worldwide: How to best protect the past from storms that could both make — and destroy — history.