In the long term, Van Buren's opposition to the Patriot War contributed to the construction of healthy Anglo-American and Canada–United States relations in the 20th century; it also led, more immediately, to a backlash among citizens regarding the seeming overreach of federal authority,[182] which hurt congressional Democrats in the 1838 midterm elections.
A new crisis surfaced in late 1838, in the disputed territory on the Maine–New Brunswick frontier, where Americans were settling on long-disputed land claimed by the United States and Great Britain.[183] Jackson had been willing to drop American claims to the region in return for other concessions, but Maine was unwilling to drop its claims to the disputed territory. The British considered possession of the area vital to the defense of Canada.[184] Both American and New Brunswick lumberjacks cut timber in the disputed territory during the winter of 1838–1839. On December 29, New Brunswick lumbermen were spotted cutting down trees on an American estate near the Aroostook River.[179]
After American woodcutters rushed to stand guard, a shouting match, known as the Battle of Caribou, ensued. Tensions quickly boiled over into a near war with both Maine and New Brunswick arresting each other's citizens. 