We have fought six wars with Canada, more than with any other country. However, in four of them, we were English and they were French (the War of the League of Augsburg, the War of the Spanish Succession, the War of the Austrian Succession, and the Third Silesian War) and in the other two (the War of the American Revolution and the War of 1812) we were independent and they were English.
Also, now-forgotten flareups like the Aroostock War and the Pig War.
5. The Revolutionary War, 1775-1783: The Canadians took the side of the evil British overlords!
4. The War of 1812, 1812-1815: Vicious Canadian militia stormed Washington with the British and burned down the White House! And not only that, but their enemy forces attacked New Orleans after the peace treaty was already signed!
3. The Aroostook War, 1838-1839: Our enemies to the North tried to claim that much of Maine was theirs, prompting U.S. patriots to have to fight for our land!
2. The Pig War, 1859: This notoriously bloody war concerned a border dispute regarding the San Juan Islands, improbably located not in Puerto Rico but between Microsoft’s headquarters in Redmond, WA, and Vancouver, that Canadian city where they film all the shows on the CW Network. The suffering of the pig was great, but he was delicious anyway.
1. The Oregon Boundary Dispute: A major border dispute, from which the slogan “54’40” or Fight!” came, and that popularized the concept of “Manifest Destiny,” the war cry of those supporting U.S. claims of ownership of land all the way up to the 54th parallel.
Extra, War Plan Red: The U.S. Millitary created a plan to defend itself against the predations of the British Empire, including their lackeys to the north.