From east to west, the boundary arcs over the top of Maine, first along the St. John River, then up the much smaller St. Francis River, to its source at Lac Pohenegamook, at the tip top of the state. Then it becomes linear, following points of the compass south-southwest, until picking up the St. John River, again, following it to its source. After that, it heads to the Highlands, following the ridge between the drainage basins of the St. Lawrence River, and the Gulf of Maine, passing the boundary between Maine and New Hampshire along the way. When the Highlands boundary intersects the source of Halls Stream, considered to be the northwesternmost headwaters  of the Connecticut River, it follows this small meandering brook to where it drains into the Connecticut River itself, at the intersection of Vermont, New Hampshire, Quebec, and the 45th parallel. All of this was spelled out, more or less, in the Webster-Ashburton Treaty of 1842, signed by Lord Ashburton, the Minister Plenipotentiary on Special Mission, representing Britain, and Daniel Webster, the United States Secretary of State. The treaty was especially timely, as the disagreement over the northern border of Maine was heading towards armed conflict, dubbed the Aroostook War, which was mostly over access to the St. John River, as a conveyor for floating logs harvested from the woods.

4698 Google map.
3868 Google map.Continuing westward, after the north end of the North Line dissolves in the St. John River, the boundary follows the river until it meets its first physical crossing ten miles upstream.

4063 CLUI photo.This is the international bridge connecting the adjacent communities of Van Buren, Maine, and St. Leonard, New Brunswick.

3869 Google map.The US Port of Entry was upgraded in 2013, like many others, taking advantage of federal stimulus funds.

3870 Google map.After Van Buren, its another 25 miles to the next crossing of the line, at Madawaska.

4064 CLUI photo.This part of Maine is rich in Acadian culture. The French-speaking Acadians arrived in the New World in the 17th century. They were distinct from the French colonists that established Quebec, and spread out in a region extending from present day Nova Scotia to northern Maine. Some of them left the region to settle in Louisiana, where they became known as Cajuns.

4065 CLUI photo.The present day Acadians of northern Maine are proudly independent, and are asserting their border-spanning cultural heritage, at places like the Acadian Village Historic site, west of Van Buren.

4066 CLUI photo.Further up river is Thibodeau Island, an unoccupied evolving sand bar which now has portions in each country.

3871 Google map.There are dozens of such internationally dynamic islands in rivers and lakes that are split by the boundary. In flowing water, the border remains fixed, while the land moves around it.

3872 Google map.The next large settlement on the river, and the next road bridge crossing it, is at Madawaska, Maine, where the Madawaska River enters the St. John from the New Brunswick side.

3873 Google map.Two bridges span the boundary here, one a road bridge, and the other carrying pipelines that connect two paper plants, on either side of the line.

4067 CLUI photo.The Twin Rivers Paper Plant is really one facility, split by the boundary. Pulp is made on the Canadian side, and pumped to the US side to be turned into paper, a system that avoided the tariff for importing paper into the US.  Steam is also generated on the Canadian side, where fuel costs used to be lower, and pumped to the US plant. A total of seven pipelines connect the plants in lines running over and under the river.

4068 CLUI photo.The bridge is hemmed in by the plant on the US side, and is limited to one lane each side, coming and going. Traffic is bad, and studies are under way to expand the crossing, somehow, likely a new bridge nearby.

4069 CLUI photo.As the most “northeasterly” town in the nation, Madawaska considers itself one of the “four corners” of the USA.

4072 CLUI photo.This fact is promoted especially at Four Corners Park. The park was opened  in 2007, primarily to celebrate motorcyclists who do a four corners trip, visiting each corner of the USA in as little as 21 days. (The other corners of course are Key West, Florida; San Ysidro, California; and Blaine, Washington, at the other end of the US/Canada border).

3874 Google map.The river boundary continues westward another 21 miles to its next crossing, at Fort Kent.

3875 Google map.The Fort Kent/Clair is crossing open around the clock, with around 2,000 cars passing through every day. 

4070 CLUI photo.In 2014, a new bridge opened next to the old one, which had grown rickety, and a new USA Port of Entry was built. 

4071 CLUI photo.US Highway 1 originates here, a two-lane highway that leads all the way to the bottom of Florida.  A small park makes note of this fact.

4073 CLUI photo.

4074 CLUI photo.The St. John River at Fort Kent was the site for a few pioneering art projects about the international boundary, done by the artist Dennis Oppenheim, in 1968. He came to this northern boundary town to make the conceptual borderline visible in different ways. One work drew a three-mile long line on the river with a snow mobile. Of course that was in the winter, when the river was covered in ice and snow.

4114 CLUI photo.The blockhouse, on the river at Fort Kent, is an historic landmark, left from the Aroostook War, which raged locally for decades. The conflict reached its peak in 1839, when militia were mobilized by both sides, and this blockhouse was built as a fortification by the Americans, seeking to maintain this territory, with its rich reserves of timber, and the river to float it on.

4075 CLUI photo.Federal officials on both sides negotiated a truce before any shots were fired, and a compromised boundary was agreed upon.

4076 CLUI photo.

4077 CLUI photo.The restored blockhouse contains relics from the period, but mostly displays images of itself, in various media, and from various points of view.

4078 CLUI photo.The bridge at Fort Kent is the last border crossing on the St. John River.

3876 Google map.The border continues on the river westward for another 16 miles.

4079 CLUI photo.Then transitions to the smaller St. Francis River, heading north, towards the very top of the state.

3877 Google map.The boundary follows the twisting St. Francis  for 43 miles, with 485 official turning points, and 122 reference monuments, until its terminus at Pohenegamook Lake (after which it heads southwest, as a straight line).

3878 Google map.This territory, at the top of Maine, is known as the North Maine Woods.

4080 CLUI photo.Though it is heavily logged, in other ways it is one of the least developed regions of the continental United States. Extending north from Moosehead Lake and Baxter State Park to the Canadian border, the 3.5 million acre tract has no towns or paved roads.

4090 CLUI photo.Access to the North Woods is controlled, with manned and unmanned gates at its dozen or so entry points. The roads within it are considered private, built by and for logging companies, and a fee is charged for access.

4089 CLUI photo.The land is mostly owned by a few companies, including the Irving Company, the New Brunswick-based oil and paper company, and the Seven Islands Land Company, which manages a million acres owned by the Pingree family.

4111 Google map.The international boundary follows the St. Francis River around the extreme northeast corner of Maine, and around the North Maine Woods. It is a tight meandering stream, with occasional lakes, and there are no roads, railways, or even dams that cross it. Forest on the USA side, and agriculture on the Canada side.

3879 Google map.The stream terminates a few yards shy of Pohenegamook Lake, in Canada, next to the communities of Sully and St. Eleuthere, also in Canada.  And a small community just barely inside the US, called Estcourt.

3880 Google map.This is the top of Maine.

4091 CLUI photo.Though it is in the US, Estcourt is only accessible by roads from the Canadian side, or via the private logging roads of the North Maine Woods.

4092 CLUI photo.There is a USA Port of Entry, at the southern end of town, just before the road from the North Main Woods meets the pavement on the Canadian side. It is clearly meant for people coming from Canada, southbound into the North Woods, something that happens only occasionally, and mostly when logging trucks go back and forth, hauling logs from the Woods into Quebec (there is a log yard across from the station on the Canadian side).

4093 CLUI photo.However, the USA Port of Entry is very busy with another function: attending to a nearly continuous stream of cars coming to the USA side of Estcourt to buy cheap American gasoline. After checking in at the US Point of Entry, Canadian gas buyers drive back up the same road they came in on, Rue de la Frontiere, which is entirely in Canada, towards the gas bar, as such places are called by Canadians.

4115 CLUI photo.The gas bar is the only business on the US side of the line in Estcourt, and might be the only gas station in the USA that displays its rate in Canadian dollars per liter. It is also posted with a sign, in French, that says “Before entering the United States all vehicles crossing the border have to register at American customs before filling up. Thanks!”

4116 CLUI photo.Turning south off the main road, to get to gas bar, you re-enter the US, through an open gate, and approach the gas pumps.

4094 CLUI photo.

4095 CLUI photo.After filling up, the cars drive out the gate, back into Canada, and head northeast on Rue de la Frontiere.

4117 CLUI photo.Then stop to report at the Canadian Port of Entry, before heading back under the railway bridge, into the rest of Canada.

3881 Google map.Rue de la Frontiere, known to the Americans as Estcourt Road, runs along the northwest side of the boundary, separated from the rest of the Canadian community of Pohenegamook by a raised railroad roadbed, with only one tunnel under it. This isolated part of town has several homes on the Quebec side, and several homes, barns and sheds on the Maine side. It also has several homesteads right on the line.

4096 CLUI photo.The front of a small house at 1183 Estcourt Road, in Pohenegamook, Quebec, is in Canada, but the back bit, including the porch and the vegetable garden, is in Estcourt, Maine.

4081 CLUI photo.The International Boundary Commission has placed a plaque on the house, at the precise point where the line hits the house.

4082 CLUI photo.The house next door is completely in Canada, just barely.

4083 CLUI photo.But the line hits the house next to it, a few inches to the right of the middle window.

4112 CLUI photo.It then passes through this backyard (most of the deck is in Canada, but the pool is in the United States).

4113 CLUI photo.The line passes through a few more back yards and porches.

4103 CLUI photo.Then it hits the back of another house.

4102 CLUI photo.And then another, going right through the side door.

4104 CLUI photo.And through the middle of the house next to that.

4118 CLUI photo.And out the other side, a few inches to the right of the big window. People who own these line homes are well aware of where the line is on their property, as they pay taxes proportionally to each government.

4105 CLUI photo.Crossing a side street the line continues northeast, narrowly missing a shed (in Canada).

4106 CLUI photo.But then striking a house, placing the addition with the side door in Canada, and the rest of the structure in the United States. In total the boundary has passed directly through five houses in town, and through more than a dozen back yards, sheds, and porches. Nearly everyone in town, no matter how much of their house is in the USA, is distinctly francophone.

4107 CLUI photo.The line then enters Parc de la Frontiere/Border Park, at the end of Estcourt Road. The very top of Maine is in the river behind the sign, between the two bridges.

3909 Google map.The boundary following the St. Francis River, coming up from the southeast, makes a turn in the river, next to the park, where it meets the top of the Southwest Line, which heads, as expected, southwestward. The intersection is between two bridges, a footbridge that spans the border over the St. Francis, and a rail bridge that is entirely in Canada. Beyond the rail bridge is Pohenegamook Lake, the source the St. Francis River, defined in the treaty as the northern turning point for the boundary. The fact that the turning point occurs a hundred yards before the lake is the result of later landfilling on the Canadian side, to build the roadbeds for the train and highway.

4108 CLUI photo.The footbridge leaves the park from the US side, and travels over the river into Canada. The bridge was washed away in a flood years ago, and there was some uncertainty about rebuilding it, as it enables people to cross the border at a place where there is no Port of Entry. However, it was rebuilt, for pedestrians only, and enables people from the cut-off part of Estcourt to get to church and other places in the main part of town more directly, even if they are doing so by entering the USA, briefly.

4109 CLUI photo.The boundary emerges from the river, and passes through the northernmost monument in Maine, located in Border Park, marking the north end of the Southwest Line portion of the Boundary.

3910 Google map.The Southwest Line heads southwest through the community of Estcourt.

3882 Google map.And onward, for 85 miles. The boundary line here, on the northwest edge of Maine, reflects one of the fundamental paradoxes of this border. On one hand, this region is a remote logging wilderness and the cold, northern edge of the USA. On the other hand it is the warm, southern edge of Canada, some of the best farm country in the nation, along the fertile St. Lawrence basin. On the US side is the woods, accessible from below only by dirt roads. On the Canadian side, the land is divided into long narrow farms, within a network of evenly spaced public roads.

3883 Google map.After Estcourt, the only official border crossing on the Southwest Line is 45 miles away, at a logging yard, in St. Pamphile, Quebec.

4119 CLUI photo.It is on a dirt road, and is used by logging trucks, bringing logs out of the North Maine Woods. After the US Port of Entry at the boundary is the company check station for the Woods, where permits are issued to enter.

4110 CLUI photo.

3884 Google map.20 miles further down the line is a settlement on the Canadian side, and a lake, both called Lac Frontiere. The Northwest Branch of the St. John River comes out of this lake, and crosses the boundary. This was the point where, according to the Webster-Ashburton Treaty, the Southwest Line ends, and becomes a more southerly line, known as the South Line. Concerning this point, the specific and convoluted language of the treaty reads: “[from the] outlet of the Lake Pohenagamook; thence, southwesterly, in a straight line to a point on the northwest branch of the river se John, which point shall be ten miles distant from the mainbranch of the se John, in a straight line, and in the nearest direction; but if the said point shall be found to be less than seven miles from the nearest point of the summit or crest of the highlands that divide those rivers which empty themselves into the river Saint Lawrence from those which fall into the river Saint John, then the said point shall be made to recede down the said northwest branch of the river se John, to a point seven miles in a straight line from the said summit or crest; thence, in a straight line, in a course about south eight degrees west, to the point where the parallel of latitude of 46°25' north, intersects the southwest branch of the St. John's; thence, southerly, by the said branch…” The result is that, from here, the South Line extends for 20 miles, until the boundary joins the channel of the Southwest Branch of the St. John River.

3885 Google map.Along the way is the Daaquam border crossing into the North Maine Woods, closed in 2004, though its Port of Entry buildings remain. The road is gated and blocked with concrete barriers on the US side.

3886 Google map.A few miles further south is the St. Juste Crossing, which absorbed the limited traffic from Daaquam, open to serve the logging industry, with two log yards on the Canadian side.

4097 CLUI photo.Like the four other official crossings on this remote western side of northern Maine, the crossing is open during business hours only, and there is a checkpoint for entering the North Maine Woods beyond the US Port of Entry.

4098 CLUI photo.The cut line continues along the South Line from the St. Juste Crossing for another ten miles, to the Southwest Branch of the St. John River.

3890 Google map.Once the South Line intersects the Southwest Branch of the St. John River, the international boundary becomes watery again, and follows the river for 35 meandering miles. This is the upstream reaches of the same St. John which serves as the boundary in northeastern Maine, through Fort Kent, Madawaska, and Van Buren.

3889 Google map.This upper Southwest Branch of the St. John is a much smaller river, becoming a stream, with considerable meanders. Much of it is narrow and shallow enough to walk across, which, no doubt, some people do. The straight cut-lines along the hundred miles of the Southwest and South Lines, are studded with camera stations (some of which are mounted on moose hunting platforms), that enable border patrols to monitor that part of the boundary nearly completely, in theory, if not in practice (details about coverage is kept secret). The meanders of the upper St. John, and the Highlands make remote monitoring very difficult. Here border patrols rely more on motion sensors and agents in the field, on foot and in ATVs. And aircraft.

3887 Google map.There is a closed crossing along this stretch of boundary, at Gilbert Road, with an unmaintained bridge over the river.

3888 Google map.There is only one open crossing on the 35 miles of the Southwest Branch of the St. John portion of the boundary, at St. Aurelie, another entrance into the North Maine Woods, used for logging.

4099 CLUI photo.

3891 Google map.A few miles further south is Little Saint John Lake, considered to be the source of the Southwest Branch of the St. John River. From this point, according to the Webster-Ashburton Treaty, the international boundary leaves the river, and follows the Highlands.

3892 Google map.The Highlands is the divide between watersheds, where on one side water flows to the St. Lawrence River, through Quebec, and on the other side to the Gulf of Maine and Atlantic Ocean. Traveling over the top of the ridge line for more than 120 meandering miles, this section of boundary is among the most remote and unmonitored on the whole continental line. Because it meanders, like a river, but is on dry land, it has more monuments than any other section of the boundary.

3893 Google map.There are four official crossings along the Highlands, the first, the Ste.-Zacharie border crossing, just two miles south of Little Saint John Lake, is the last of the dirt road logging industry Ports of Entry into and out of the North Maine Woods.

4120 CLUI photo.

3894 Google map.From there the boundary meanders for 35 miles before the next crossing, the Jackman/Armstrong Border Crossing, on Highway 201.

3895 Google map.This, the first paved crossing over the border since Fort Kent, is the busiest crossing on the western side of Maine.

4100 CLUI photo.Just north of the Jackman/Armstrong Border Crossing is a hunting camp, on the Canadian side, where the line goes through one of the cabins. This is the sixth inhabited structure with the international boundary running through it, so far.

3896 Google map.From the Jackman/Armstrong Border Crossing its another nearly 50 miles of remote Highlands terrain until the border meets another official road crossing, the Coburn Gore/Woburn crossing, the second of two paved road crossing points on the western side of Maine.

3897 Google map.As at many of the remote Ports of Entry along the boundary, there is a small row of government housing for the customs officers.

4101 CLUI photo.The Coburn Gore/Woburn Crossing, is the last of the 24 official crossings in Maine. From the Port of Entry, the line heads south into the cutline through the Highlands.

3898 Google map.The border meanders through the Highlands for another 25 miles, when it meets the state line for New Hampshire.

3899 Google map.

3900 Google map.The international boundary at the top of New Hampshire is 58 miles of meandering, mostly following the drainage divide between the St. Lawrence River, and the Connecticut River.

3901 Google map.Along the way is just one official border crossing point, the Pittsburg/Chartierville crossing on Route 3.

4121 CLUI photo.Despite the fact that it is the only crossing in New Hampshire, only around 10,000 vehicles pass through here a year.

4088 CLUI photo.There is an unusual double monument on the border at New Hampshire’s only crossing, with two obelisks, 18 inches apart, emerging from a single concrete base. The explanation is an often told tale where two 19th century boundary surveying teams, coming from either direction, one Canadian and one American, met here, and found their lines differed by 18 inches. Rather than split the difference, two monuments were installed, #483, and #484. Eventually the bases of the monuments were cemented together, forming one official marker, surrounded by a fence, which further unites them.

4086 CLUI photo.This story of precision and international camaraderie turns out to be apocryphal. The more accurate version, according to an IBC Commissioner, is that they had an extra monument, and thought it would make a nice story.

3902 Google map.The Highlands boundary continues along the ridge past the crossing, dividing the rugged wooded mountains of northern New Hampshire, from the flat arable plains of Quebec’s Eastern Townships, for another 20 miles.

3903 Google map.It ends, at its westernmost point, at the upper reaches of Halls Stream, considered to be the northwestern-most headwaters of the Connecticut River.

3904 Google map.The boundary becomes a watery one again, following the stream for the next 25 miles. Marking the border along this tiny, meandering stream is another challenge for the International Boundary Commission.

3905 Google map.The 1842 treaty identifies the “middle of Halls Stream” as the boundary. By the time it was resurveyed in 1908, the river had shifted more than 600 feet in some places. By 1979, more than half of the 467 turning points logged and marked with shoreline reference points along the stream were now on land.

3906 Google mapAlong Halls Stream, the border is a double set of meanders, one is the boundary as a recording of the stream made in the 1909 survey, the other the stream as it is now.

4084 CLUI photo.The recorded boundary meanders through what are now fields and meadows, often unmarked, and possibly even unknown to landowners, who assume that the boundary is the stream, not in the middle of their lawn.

4085 CLUI photo.

3907 Google map.The stream finally meets its end as the international boundary when it intersects the 45th parallel near Beecher Falls, Vermont. This point was established by the 1783 Treaty of Paris, which declared that the boundary will be located where the “northwesternomst head of the Connecticut River meets the 45th parallel.” The boundary westward from here continues along the 45th parallel along the top of Vermont, which begins on the west bank of Halls Stream, next to an Ethan Allen furniture factory.