10 minutes later you have a Visa good for three years. Normally one expects lots of bureaucracy when dealing with the government, but the US/Canada have really streamlined their NAFTA (North American Free Trade Agreement) down to next-to-no hoops to jump through.
Regardless of what they say, you always calmly reply with the following mantra, "My period of employment is for a period of up to 3 years [note: used to be one year]", at which point my plan is to return home to Canada.
Every statement you make with immigration must be some variant of that, and you must never, ever, suggest that there is the slightest thought/plan of staying past your limited visa, even if you plan to do that by re-applying.
With the exception of the first couple years (where I was rejected twice), I've never had to spend more than 10 minutes at immigration. I will admit the confrontational attitude does get your heart racing...