i grew up in a border town (across a big river from michigan) and yes, even without taking the accent into account (they had a markedly different accent from ours, though they were so close geographically), it was pretty much immediately apparent when you were dealing with an american--they tend to be louder, more effusive, more "assertive", and even gesticulate more than canadians. also, a lot of them seemed to be horrible drivers--either that, or when they came over they were so confused by our traffic signs (speed limits in km/h) they forgot how to drive. ...though that fails to explain why their driving was so horrible when we would visit them on their side of the border. 