Negotiated in the US federal capital city of Washington, DC, it was signed August 9, 1842, under the new administration of US President John Tyler, who as the former vice president, had just recently succeeded and became chief executive upon the unexpected death of his running mate and predecessor, William Henry Harrison, who had only served a single month in office.

The Daniel Webster–Lord Ashburton negotiations and new drawn-up 1842 treaty resolved many of the issues of the recent border conflicts and skirmishes between Americans and New Brunswickers in the Aroostook War of 1838–1839.

It arose from disputes and controversies over the vague indefinite terms and text of the old peace agreement of the Treaty of Paris of 1783, which ended the American Revolutionary War.

The treaty was signed by US Secretary of State Daniel Webster, and British diplomat Alexander Baring, 1st Baron Ashburton.

[2] This treaty marked the end of local confrontations between lumberjacks (known as the Aroostook War) along the Maine border with the British colonies of Lower Canada (which later became Quebec) and New Brunswick.

The British were assigned the Halifax–Quebec road route, which their military desired because Lower Canada had no other connection in winter to New Brunswick and Nova Scotia.

The Webster–Ashburton Treaty failed to clarify ownership of Machias Seal Island and nearby North Rock, which remain in dispute.

Ambiguity in the map and treaty resulted in Minnesota's Arrowhead region being disputed between the two nations years later, and previous negotiations had not resolved the question.

[citation needed] This 1842 treaty reaffirmed the border and further defined it by modifying the border definition to instead read as: ... at the Chaudiere Falls, from which the Commissioners traced the line to the most northwestern point of the Lake of the Woods, thence, along the said line to the said most northwestern point, being in latitude 49°23′55″ north, and in longitude 95°14′38″ west from the Observatory at Greenwich; thence, according to existing treaties, due south to its intersection with the 49th parallel of north latitude, and along that parallel to the Rocky Mountains ...The Webster–Ashburton Treaty failed to deal with the Oregon question, although the issue was discussed in negotiations.

In addition, the United States did not press for the return or extradition of an estimated 12,000 fugitive slaves who had fled the U.S. going north and reached British territory in Canada.

However, the news of the ratification of the British-American international treaty did not reach either of the two parties further west, involved in negotiating the land cession.

It showed contested areas of that time during the original 1783 Paris Treaty negotiations largely resolved in favor of the United States.