Actually, as one Canadian once pointed out to me, the US and Candad already tried having a war, the War of 1812. It was pretty much of a draw, really. The Canadians captured Mackinaw Island, but we got it back in the treaty, Detroit changed hands a couple of times, Lundy's Lane was pretty much of a draw, the Canadians retained the field of battle, but both sides suffered pretty sever casualties. Nope, actually the only places where the US really came out ahead were the Battle of Lake Erie, and New Orleans. New Orleans may not count, technically since it was fought after the treaty was signed, and it pitted Andy Jackson's Americans against Packenham's English and Scots.

All in all, I think it's probably a pretty bad idea. Nothing for either side to gain, eh?