The series of official boundary maps consists of 256 individual maps duly signed and approved by both Commissioners. Along with the companion reports, they are the official description of the boundary. To ensure efficient and orderly management of boundary maintenance activities, the boundary is split into 8 sections and 29 sub sections corresponding to areas with homogeneous characteristics. Official maps and the most recent geodetic coordinates of the international boundary can be viewed and downloaded from this section.
A - Source of the St. Croix River to the Atlantic Ocean
This section extends from Passamaquoddy Bay in the Atlantic Ocean to the source of the St. Croix River located in Aroostook County, Maine, and Carleton County, New Brunswick. Its relatively short 250-kilometre (154-mile) length winds through the bay’s islands and then follows along the deepest channel of this historic waterway.
B - Source of the St. Croix River to the St. Lawrence River
From the source of the St. Croix river, the boundary follows watercourses, height of land and approximates the 45th parallel of latitude until it reaches the St. Lawrence river in Akwesasne.
C - St. Lawrence River and the Great Lakes
The boundary in the St. Lawrence River and the Great Lakes is a maritime boundary with numerous turning points defined by reference marks and lighthouses on the shore. This section was originally surveyed from 1817 to 1820 by David Thompson and William Bird, pioneers in the field of geomatics. The 29 maps depicting this section were prepared by the now defunct International Waterways Commission.
D - The Northwesternmost Point of Lake of the Woods to Lake Superior
From Lake Superior, the boundary passes through 32 lakes and as many connecting rivers before reaching Rainy River, where it snakes through rich farmlands before reaching Lake of the Woods, renowned for its recreational vocation.
E - Gulf of Georgia to the Northwesternmost Point of Lake of the Woods
The 49th Parallel boundary, east of the Rocky Mountains, was originally surveyed during the years 1872 to 1875. Determination of the parallel of latitude was by astronomic observations carried out at about 32-kilometre (20-mile) intervals. The final survey and mapping of the boundary, along the western end of the 49th Parallel, was completed in 1912 and 1913. Separating 5 provinces, one territory and 6 American states, the border that runs along the 49th parallel crosses the most varied terrain ranging from the fertile prairies to the highest peaks of the Rockies from where it descends to meet the Pacific at Boundary Bay
F - Forty-ninth Parallel to the Pacific Ocean
From the West Coast, this maritime section of the border snakes its way through the islands of the Strait of Georgia and then between Vancouver Island and the state of Washington in Juan de Fuca strait to reach the open sea in the Pacific Ocean.
G - Tongass Passage to Mount St. Elias
From the Pacific Ocean, the border travels up to the head of the Portland Canal where it makes landfall and takes the high road over a series of mountain peaks parallel to the coast about 48 kilometres (30 miles) inland until it intersects with the 141st Meridian at Mount St. Elias. Although it travels over many perpetual snowfields, numerous rivers lined with heavy timber cross its path between mountain peaks.
H - Arctic Ocean to Mount St. Elias
Following the 141st Meridian in a straight line, the border runs its course for 1 045 kilometres (650 miles) from the Arctic Ocean to Mount St. Elias. It runs through the taiga in the boreal part, riding some cliffs near the Yukon River and then cuts through a mixed forest that becomes less stunted in its southern section. The scarcity of roads complicates maintenance.