You know, this would be the second time the US and Canada went to war! I grew up near one of the old forts established dureing the famous(?) Aroostook War. I took the following from: http://homepages.rootsweb.com/~godwin/reference/aroostook.html
The Aroostook War was an undeclared, bloodless "war" that occured in 1839. The peace treaty in 1783 had not satisfactorily determined what is the boundary between New Brunswick and what is now Maine. The boundary dispute worsened after Maine gained statehood (1820) and, disregarding British claims, began granting land to settles in the valley of the Aroostook River. The king of the Netherlands was asked to arbitrate the disbute, but the U.S. Senate rejected his award in 1832, although the British accepted it.
Canadian lumberjacks entered the Aroostook region to cut timber during the winter of 1838-1839, and in February they seized the American land agent who had been dispatched to expel them. The "war" was now under way. Maine and New Brunswick called out their militiamen, and Congress, at the instigation of Maine, authorized a force of 50,000 men and appropriated $10 million to meet the emergency. Maine actually sent 10,000 troops to the disputed area. President Martin Van Buren dispatched General Winfield Scott to the "war" zone, and Scott arranged an agreement (March 1839) between officials of Maine and New Brunswick that averted actual fighting. Britain agreed to refer the dispute to a boundary commission, and the matter settled in 1842 by the Webster-Ashburton Treaty.
The compromise reached by Daniel Webster and 1st Baron Ashburton (Alexander Baring) awarded 7,015 square miles to the United States and 5,012 to Great Britain. Retention by the British of the northern area assured them of year-round overland military communications with Montreal. Webster used a map, said to have been marked with a red line by Benjamin Franklin at Paris in 1782, in persuading Maine and Massachusetts to accept the agreement. Britain agreed to pay these states $150,000 each, and they were to be reimbursed by the United States for expenses incurred defending the area against encroachment.