At the start of John Quincy Adams's presidency, the boundary line between the territory of the United States and British North America (Canada) remained undetermined in several places. Negotiations between American and British ministers in the summer of 1827 provided a framework for resolving these issues, although no final agreements were reached until the 1840s.
The two main areas of contention were the boundary between northern New England and Canada and the status of the Oregon country. President Adams had dispatched Albert Gallatin to London in 1827 to attempt to negotiate an end to an ongoing trade crisis between Britain and America. While Gallatin was not successful in resolving this issue, he did enter into negotiations about the boundary issues with British commissioners H.V. Addington and Charles Grant. Two conventions were produced.
First, on August 6, 1827, America and Britain agreed to continue the "free and open" use of the Oregon country – roughly the area of present-day Washington State and British Columbia. This agreement was a continuation of the joint-sovereignty arrangement established in the Convention of 1818. This Convention remained in effect until the mid-1840s, when the question of the Oregon country was raised by President James Polk.
On September 29, 1827, a second convention was agreed to, this one establishing a framework for defining the boundary of the northeastern United States. There were two disputed areas. First, the exact source of the Connecticut River needed to be agreed to, in order to fix the boundary between New Hampshire and Quebec; there were about 100,000 acres of land in dispute here. Second, a 100-mile stretch of boundary between Maine and New Brunswick was the subject of another dispute that went back to the Treaty of Paris (1783). There were over seven and a half million acres of land at stake in this controversy.
According to the Convention, both boundary disputes would be subject to arbitration by a third party sovereign state. This was agreed to. The King of the Netherlands was eventually chosen to serve as arbitrator. In 1831, he found both nations' claims inconclusive, but offered to mediate the dispute by dividing the territory along the Maine boundary in half. Both Andrew Jackson and the U.S. Senate rejected this. The present boundary between Maine and New Brunswick was eventually agreed to in the Webster-Ashburton Treaty (1842).
James E. Lewis, Jr., John Quincy Adams: Policymaker for the Union (Wilmington, Delaware: Scholarly Resources, 2001)
Lester H. Burne, ed., Chronological History of United States Foreign Relations, 1776 to January 20, 1981 (New York: Garland Publishing, 1985).