Webster-Ashburton Treaty Settles Maine’s Canadian Border Summary

  • Last updated on November 10, 2022

This settlement of a long-standing U.S.-British dispute over the border between Maine and New Brunswick set a precedent for amicable relations between North American neighbors that would reap dividends in the Oregon settlement four years later.

Summary of Event

The Webster-Ashburton Treaty settled a boundary controversy that had irritated Anglo-American relations since the Treaty of Paris Paris, Treaty of (1783);and Canadian border[Canadian border] had been signed to end the Revolutionary War American Revolution (1775-1783);settlement of in 1783. The dispute involved the question of sovereignty over portions of northern Maine and the colonial Canadian province of New Brunswick. The area involved was not large, and the region was remote and lightly populated, but between 1783 and 1842, conflicts between America and Great Britain repeatedly intruded to prevent some rational settlement of the border dispute. Webster-Ashburton Treaty (1842)[Webster Ashburton Treaty (1842)] Maine;borders New Brunswick;borders Ashburton, First Baron Webster, Daniel [p]Webster, Daniel;and Webster-Ashburton Treaty[Webster Ashburton Treaty] Great Britain;and United States[United States] Borders, U.S.;with Canada[Canada] Canada;borders British Empire;and Canada[Canada] [kw]Webster-Ashburton Treaty Settles Maine’s Canadian Border (Aug. 9, 1842) [kw]Ashburton Treaty Settles Maine’s Canadian Border, Webster- (Aug. 9, 1842) [kw]Treaty Settles Maine’s Canadian Border, Webster-Ashburton (Aug. 9, 1842) [kw]Settles Maine’s Canadian Border, Webster-Ashburton Treaty (Aug. 9, 1842) [kw]Maine’s Canadian Border, Webster-Ashburton Treaty Settles (Aug. 9, 1842) [kw]Canadian Border, Webster-Ashburton Treaty Settles Maine’s (Aug. 9, 1842) [kw]Border, Webster-Ashburton Treaty Settles Maine’s Canadian (Aug. 9, 1842) Webster-Ashburton Treaty (1842)[Webster Ashburton Treaty (1842)] Maine;borders New Brunswick;borders Ashburton, First Baron Webster, Daniel [p]Webster, Daniel;and Webster-Ashburton Treaty[Webster Ashburton Treaty] Great Britain;and United States[United States] Borders, U.S.;with Canada[Canada] Canada;borders British Empire;and Canada[Canada] [g]British Empire;Aug. 9, 1842: Webster-Ashburton Treaty Settles Maine’s Canadian Border[2260] [g]Canada;Aug. 9, 1842: Webster-Ashburton Treaty Settles Maine’s Canadian Border[2260] [g]United States;Aug. 9, 1842: Webster-Ashburton Treaty Settles Maine’sCanadian Border[2260] [c]Diplomacy and international relations;Aug. 9, 1842: Webster-Ashburton Treaty Settles Maine’s Canadian Border[2260] [c]Expansion and land acquisition;Aug. 9, 1842: Webster-Ashburton Treaty Settles Maine’s Canadian Border[2260] McLeod, Alexander Sparks, Jared Tyler, John [p]Tyler, John;and Webster-Ashburton Treaty[Webster Ashburton Treaty]

The boundary problem arose from ignorance about the geography of the northeastern region and of the failure of the negotiators at Paris in 1783 to attach maps to the treaty with boundary lines clearly marked upon them. The treaty language stated that the boundary between Maine and New Brunswick was to be the St. Croix River from Passamaquoddy Bay to its source, and then “a line drawn due north, from the source of the St. Croix River, to the Highlands which divide those rivers which empty into the River St. Lawrence from those which fall into the Atlantic Ocean.” The problem was that British and American surveyors could not agree on which of two streams emptying into Passamaquoddy Bay was the St. Croix River. Moreover, the “highlands” mentioned in the treaty were not identified clearly enough to satisfy either side. As a result, until the boundary was definitely fixed, the inhabitants of an area of approximately 7.7 million acres did not know whether they owed allegiance to Canada or to the United States.

Over the years, numerous efforts were made to settle the conflict. One provision of Jay’s Treaty in 1794 Jay’s Treaty of 1794[Jays Treaty of 1794] was for a mixed commission to identify the “real” St. Croix River and chart its course. Its findings, which offered a compromise solution to the dispute, were made part of a general convention signed in 1803. However, the U.S. Congress refused to ratify the agreement, largely because of an article in the agreement dealing with the Northwest boundary question involving Oregon.

No further attempt to resolve the border dispute was made until the negotiations at Ghent Ghent, Treaty of (1815);and Canadian border[Canadian border] War of 1812 (1812-1814);Treaty of Ghent in 1814 were undertaken to end the War of 1812. At Ghent, the British tried hard to win a favorable Canadian boundary settlement because the recent war had made them aware of the importance of the area for the construction of a projected military highway from Montreal Montreal;roads and Quebec Quebec;roads to the Maritime Provinces Maritime Provinces;transportation . The United States refused to accede to British demands, and all that the peace treaty accomplished on the border matter was to create four commissions to mark the entire boundary Great Lakes region;borders from the Atlantic to the Lake of the Woods, west of Lake Superior. With regard to the Northeast, the treaty provided that, should the commission fail to agree, the question would be given over to arbitration by a third state.

When the joint commission failed to reach agreement, King William I William I (king of Netherlands) of the Netherlands was asked to arbitrate the matter in 1827. The Dutch ruler proposed a division of the disputed territory almost equally between the two parties. Great Britain was willing to accept this compromise, as was U.S. president Andrew Jackson, Jackson, Andrew [p]Jackson, Andrew;and Canadian border[Canadian border] but the states of Maine and Massachusetts opposed a solution that gave away a large piece territory that they regarded as part of Maine. Jackson then submitted the issue to the U.S. Senate, which rejected the solution that had been proposed by King William. Political pressures and concern for national prestige prevented the issue from being resolved for another decade.

The 1830’s witnessed numerous incidents related to the boundary issue, which further heightened the tension between the United States and Great Britain. The Canadian insurrection of 1837 Canada;rebellions elicited great sympathy from Americans along the frontier, and the Caroline affair Caroline affair (in which a U.S. citizen, Amos Durfee Durfee, Amos , was killed on U.S. soil by Canadians assisting British authorities) inflamed opinion against Great Britain throughout the United States. The arrest and trial in 1840 of Alexander McLeod McLeod, Alexander , a Canadian deputy sheriff, for the murder of Durfee, which most historians believe he did not commit, brought anti-British sentiment to a peak and stood in the way of any compromise on the boundary issue. Great Britain threatened war if McLeod was convicted. McLeod was acquitted and the threat passed, but the incident underscored the danger of letting the tension between Great Britain and the United States over Canadian border issues continue to simmer.

More directly related to the dispute was the so-called Aroostook War Aroostook War (1838-1839) —a threatened conflict between Maine and New Brunswick forces in 1839. The fertile Aroostook Valley was the scene of incidents of claim-jumping and furious competition for timber and land during this period, and there was increasing violence. The danger of an armed clash was averted through a truce arranged by General Winfield Scott, but the basic problems remained to imperil the peace.

The conflict was finally resolved in 1841, soon after Daniel Webster became secretary of state and Baron Ashburton, who had married a Philadelphia heir and had extensive financial interests in the United States, was appointed special envoy for Great Britain with powers to resolve the boundary controversy. Ashburton’s appointment signified the British government’s increased concern for Canadian issues. In the aftermath of Lord George Durham’s report, which had called attention to Great Britain’s previous neglect of the Canadian situation, the British government was determined to take Canadian matters in hand. Ashburton was instructed to negotiate amicably with the United States and to settle the border issue once and for all.

Even before Ashburton’s arrival, Webster had announced that the United States would consider a compromise boundary in the Northeast. As pro-British as any U.S. politician of his era, Webster was convinced that the dispute must be settled. To do so, however, the McLeod McLeod, Alexander case would have to be resolved and the state of Maine would have to be persuaded to accept a surrender of territory that it claimed as its own. McLeod was acquitted by a New York jury, but direct intervention by Webster was required to accomplish the second aim.

The negotiation of the Canadian border treaty was a high personal priority for Webster. He saw it as the capstone of his tenure as secretary of state and prolonged his tenure in that office solely in order to negotiate the treaty. William Henry Harrison, the Whig president who had appointed him to the State Department, had died in 1841 after only one month in office, leaving the presidency to Vice President John Tyler Tyler, John [p]Tyler, John;and Webster-Ashburton Treaty[Webster Ashburton Treaty] , who was a Democrat by party. Most members of Harrison’s cabinet were Whig Party (American) Whigs, and most resigned when Tyler showed that he had no intention of following Whig policies. Although Webster was also a Whig, he stayed on because he saw the negotiation of the treaty with Great Britain as a vital diplomatic necessity.

Webster and Ashburton began informal conversations in the autumn of 1841 and made rapid progress. They agreed to “split the difference” over the territory in dispute between Maine and New Brunswick. The United States won the line north of 45 degrees north latitude as the boundary of New York New York State;Canadian border and Vermont. Vermont;Canadian border Minor adjustments were made in the region of Lake of the Woods in Minnesota Minnesota;Canadian border and articles dealing with extradition, suppression of the international slave trade, and the Caroline affair were drafted.

The objections of Maine and Massachusetts to a compromise settlement, which were overcome only after strenuous efforts, resulted in the federal government’s paying $150,000 to each state. Jared Sparks Sparks, Jared , a noted historian, lobbied for the treaty in the Maine legislature, for which he was paid $14,500 by Ashburton. Signed on August 9, 1842, the treaty was approved by the U.S. Senate fewer than two weeks later.


The Webster-Ashburton Treaty was an important achievement. It removed a source of potential international conflict and brought about an immediate improvement in Anglo-American relations. Historians agree that settlement of the Oregon controversy four years later would have been exceedingly difficult without use of the Webster-Ashburton Treaty as a precedent. Nevertheless, the negotiations, or more precisely Webster’s role in them, are accounted by some as a failure in United States diplomacy. By the treaty’s terms, the United States conceded approximately 5,000 of the disputed 12,000 square miles of territory to Great Britain. There now exists strong evidence (much of which was available to Secretary of State Webster, had he wished to uncover it) to support the validity of the original U.S. claims. On the other hand, concessions made by Ashburton in the Lake of the Woods region gave the United States clear title to 6,500 square miles of territory that later revealed valuable deposits of iron Iron;in Maine[Maine] ore.

The United States had fought two previous wars against British troops based in Canada. The Webster-Ashburton Treaty did much to ensure that no similar conflicts would ever happen again. Although Webster was accused of sacrificing more territory to the British than necessary, his flexibility no doubt contributed to British willingness to let the United States have the richest portions of the Oregon Territory only a few years later. Webster and Ashburton did much to guarantee the unprecedented amity and peace that prevailed on the United States-Canadian border in the centuries after their agreement.

Further Reading
  • citation-type="booksimple"

    xlink:type="simple">Bourne, Kenneth. Britain and the Balance of Power in North America, 1815-1908. Berkeley: University of California Press, 1967. Adds a valuable perspective on the border dispute, but misleadingly implies that all the diplomatic cards were in Great Britain’s hands.
  • citation-type="booksimple"

    xlink:type="simple">Dunbabin, John P. “The 1831 Dutch Arbitration of the Canadian-American Boundary Dispute: Another View.” New England Quarterly 75, no. 4 (2002): 622-646. Draws extensively on Dutch documents to analyze the role of the Netherlands in the effort to resolve the Maine-New Brunswick border dispute.
  • citation-type="booksimple"

    xlink:type="simple">Jones, Howard. To the Webster-Ashburton Treaty: A Study in Anglo-American Relations, 1783-1843. Chapel Hill: University of North Carolina Press, 1977. Argues that the treaty ended the animosity between the United States and Great Britain.
  • citation-type="booksimple"

    xlink:type="simple">Peterson, Merrill D. The Great Triumvirate: Webster, Clay, and Calhoun. New York: Oxford University Press, 1987. Study of three outstanding early nineteenth century American statesmen that examines Webster’s motives during the treaty negotiations.
  • citation-type="booksimple"

    xlink:type="simple">Remini, Robert V. Daniel Webster: The Man and His Time. New York: W. W. Norton, 1997. Important biography of Daniel Webster that provides a meticulously researched and balanced portrayal.
  • citation-type="booksimple"

    xlink:type="simple">Sassaman, Richard. “A Borderline War.” American History 35, no. 6 (2001): 20-27. Concise discussion of the Maine-Brunswick boundary dispute its origins to its successful resolution in 1842.
  • citation-type="booksimple"

    xlink:type="simple">Stevens, Kenneth R. Border Diplomacy: The Caroline and McLeod Affairs in Anglo-American-Canadian Relations, 1837-1842. Tuscaloosa: University of Alabama Press, 1989. Most important work to date on the Webster-Ashburton treaty and its diplomatic background. Gives an account of each side’s perspectives during the negotiations.

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