The wind started blowing at two in the morning. Branches and leaves ricocheted off the tent, and the trees around Diggity Stream groaned. I barely slept as gusts burst off the lake and rattled the tent poles. When I finally got up, it was 5:30 a.m.

Fog flowed from the mountains into Spednic Lake. The eastern sky was an arc of amber light. Wind roaring through the trees was thick with the dank scent of lake water turning over. Northern Maine gets cold in early October, and I had spent most of the night shivering beneath clear skies and a swirl of stars. The Milky Way ran exactly over the middle of the campsite, perpendicular to the stream. The last thing I saw before falling asleep was a shooting star splitting the sky in two.

This was day three of a 4,000-mile journey along the U.S.-Canada boundary. I grew up in northern Maine and had always been fascinated with our “forgotten border.” At 5,525 miles, including Alaska, the northern boundary is the longest land border between two nations in the world. Most of the eastern third of the line runs along rivers and lakes, like Spednic, so the best way to see it is from the water. With all of the news about growing tension along “the world’s friendliest border,” I thought it would be interesting to travel along it instead of cross it.

The temperature was 25 degrees at the campsite, and my fingers went numb as I broke down the tent and built a fire. The border cuts through Spednic, East Grand and North lakes before reaching the headwaters of the St. Croix River watershed at Monument Brook. If I could cross Spednic that morning I would likely be able to reach the headwaters — and the end of the first leg of my trip — the following day.

The waves had grown to 2 feet overnight, but the canoe handled them well. It was a 16-foot “square stern” Old Town — a design developed in the 1930s on nearby East Grand Lake. The boats were built to hold a small outboard engine for lake crossings and upstream travel. I had been advised to bring a 5-horsepower engine for this part of the trip and was relieved I did when I hit Sandy Bay 30 minutes later.

The wind blew straight down the bay, and the waves doubled in size. Halfway across, I could barely see through the spray blowing over the bow. In a lapse of judgment, I took my hand off the engine tiller and reached for my raincoat. A blast of wind knocked the canoe sideways and the engine whipped to the side. A wave hit the boat at the same instant, tipping it violently and dumping freezing water into the hull.

A mariner’s rule I learned growing up is that you have a 50 percent chance of swimming 50 yards in 50-degree water. I was around a half-mile from the closest shore when the water poured in.

I grabbed both gunwales and hung on as each wave slammed the hull, lunging from side to side to keep the canoe upright. I couldn’t see another boat on the lake. No border agents, fishermen, rangers, nothing. Three days into my epic journey across the northern border, it looked like the trip was about to come to a grim end.

The journey begins

My adventure began three days earlier in Calais, Maine, a few miles from the easternmost tip of mainland America. When the northern border was drawn, waterways like the St. Croix, St. Lawrence, Niagara and Rainy rivers were America’s highways. They acted as conveyor belts delivering goods, resources and people from interior America to ships waiting on the coast. They were so vital to American and British-Canadian commerce that delegates at the 1783 Treaty of Paris — which ended the Revolutionary War and created the eastern half of the northern border — drew the boundary right along them and mandated that they be shared.

I unloaded my canoe near the Grand Falls flowage on the St. Croix, where a gray-haired dam worker reminded me that the river flows south and east. “Which means you’ll be going upstream,” he said.

He was right. Maine is shaped like a guillotine blade, pitched a few degrees toward the ocean. Explorers, trappers and log drivers used 10-foot black cedar shafts, harvested from bogs, to pole up the St. Croix almost as fast as they could make it down. I hoped that the outboard engine would do the same.

After years of paddling against headwinds and currents, the engine felt like an invisible hand pushing the canoe along. It was impossible to know which side of the border I was on. There wasn’t a person or border station in sight — nothing but flat, dark water under a pale blue October sky.

I got a late start and lost an hour when the propeller hit a rock. The sun was down and the St. Croix was a dark shadow by the time I made it off the flowage and into the river. The wilderness around it was dense and primitive. A beaver waddled to the shoreline and swam around the canoe as though it had never seen a human before. A few stars appeared and the channel narrowed. The current was more powerful than I’d expected, especially for October when water levels are typically low. The engine was barely strong enough to fight it, and progress was slow.

When it got too dark to see rocks, I steered blind — using muscle memory to react to subtle shifts in the current. I don’t know how long I drove like that or how far. I was lost in the effort, frozen, inching forward. At some point, the roar of the river died down and the canoe slid into a wide eddy.

A 3-foot pile of dry cordwood sat in a campsite a few feet from the river. U.S. and Canadian river associations maintain more than a dozen campsites on their respective shores. I tied up the canoe on the U.S. side, 25 feet from Canada, and lit a fire to warm up.

It got so dark an hour later that I couldn’t see the canoe or the river. The canopy blocked the stars. It was spooky to be alone so far from civilization. On a map, the boundary is a clear line. On land, it passes through impossible places — ravines, cliff bands, bogs, waterfalls, rocky summits, white water — that few people ever see.

I grew up in this country, had explored it for 20 years, and thought I knew it. But this was different. Traveling the border was like walking along an invisible wall. There were no houses, towns, roads or hiking paths. It was the end of America, and the closer I got to it the more primal it became.

Rough waters

I was reminded of that primal nature two days later, as the canoe lurched from side to side in Sandy Bay. I had given up on the St. Croix after the first day — the current was too strong to fight — and used my car to portage to Spednic Lake instead. Stuck in the middle of the lake, I began to wonder if any section of the boundary would be easy to travel.

The waves grew so tall in the bay that I couldn’t see over the next one from the trough. During a moment between swells, I leapt for the engine to get control of the canoe again. Another wave hit and I twisted the throttle. The boat spun around and rode up and over the next swell.

I ran the Canadian side of the border the rest of the way, in the lee of Norway and Hinkley Points where the water was calmer. The wind finally died near Forest City, and I beached the canoe at the town landing.

You hear a lot about border security these days, yet I crossed the border three dozen times on Spednic Lake and the St. Croix River. The only person who stopped me was an elderly woman in Forest City riding an ATV.

“Where you comin’ from?” she asked.

“The boat launch,” I answered.

“What boat launch?”

“Forest City.”

“But where did you come from?”

We stared at each other for a long moment. Then I walked away, and she roared off in the opposite direction. That night at Wheaton’s Lodge, a mile down the road, owner Patrick Patterson said, “That would be Georgie.” Georgie had called half the town after confronting me to report that someone she didn’t recognize was walking through Forest City.

Keeping an eye on you

I told Patrick that small-town, grapevine security was apparently more effective than the Border Patrol. I hadn’t seen a single agent on the lake or the river. “I guarantee you the patrol knows exactly where you are,” he said. Patrick is just under 6 feet tall and north of 200 pounds. His presence is channeled through a voice two octaves deeper than anything I’ve heard come out of a human. He is the reincarnation of Paul Bunyan, with an affection for military terms and a seemingly endless supply of one-liners.

He has owned Wheaton’s since 2012 with his wife, Sandy. When I asked him how the Border Patrol knew exactly where I was, he unfolded five meaty fingers, one at a time, and said, “Cameras. Drones. Satellites. Sensors. Air surveillance. One way or another, they’ve got eyes on you.”

I didn’t see anything on East Grand Lake the next morning as I set out on the last leg of the trip. No border agents, markers, not even fishermen. Maine’s northland was once a premier destination for outdoor sportspeople in America. Wilderness lodges in Aroostook and Washington counties helped create the concept of domestic travel in America in the late 1800s, when wealthy tycoons of the Gilded Age rode the trains they built to Augusta and Bangor to hunt and fish.

Tan stripes marked the high-water line on bluffs across from Blueberry Point. A stand of red and orange maple and oak rose over a small hill and dropped to the lakeshore. A large window at the Fosterville border crossing faced the road. I hugged the U.S. side of the channel under a small bridge between the two border stations. I glanced back from the other side and saw the top of a border agent’s head looking the other way.

Cedars swooped over a beach on the southern shore of North Lake. Water lilies and duckweed turned the water green near the mouth of Monument Brook. A massive, restored farmhouse stood on the eastern end, surrounded by pasture. The water in between was flat calm.

The boundary runs through North Lake into the brook, then to a concrete marker at its head, where it shoots due north to the St. John River. The marker is called Monument 1 and is the first of more than 900 that reach across the United States from the St. Croix to the Pacific.

There wasn’t a cloud in the sky, not in the sense of the phrase, but actually not a single vapor formation — just striations of light to lighter blue lifting from the horizon. It was the quietest place I’d been in a long time, a no man’s land on America’s forgotten border.

I turned off the engine and paddled to the mouth of Monument Brook. I wasn’t sure how far upstream I would go. The channel twisted left, then right. I made it around the first bend with a breeze at my back. There wasn’t enough water around the next turn and the canoe hit bottom. I stared into the trees for a while and waited for the stream to push the bow around. Then I paddled a few strokes, drifted into America, and followed the current back to the lake.

Porter Fox is the author of “Northland: A 4,000-Mile Journey Along America’s Forgotten Border,” which was published July 3, and from which this article was adapted.