Wow, that's really strange.  Here's another I just found online:

And another:

 

Website: http://wildaboutcarsonline.com/cgi-bin/pub9990289237970.cgi?categoryid=9990355534750&action=viewad&itemid=9990412193265

 

This is the first time I've noticed this.  Does anybody have an explanation?  This was before the auto pact of 1965 - could you order an American Pontiac through a Canadian dealer at that time?

Good work MC ! I was always under the impression that one could order a US car at the Pontiac dealers, its just that it would be imported and subject o high taxes and a high base price. 1959 was the year the Wide Track Pontiac was coined and even though in the pictures of the Canadian cars you can plainly see they don't have it, perhaps it was a marketing ploy to drive sales. There's no question that parts counter guys always asked you Blue Block ? or Orange Block ? so these US models had to be around. 

 

I know foreign brochures had both Canuck and US models.

Greaser wrote:

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My guess is that the magazine or publication that had these ads were  American publications,

(Time,Look,Life?) that were sent into Canada. GM knowing that in order to cover the Canadian market,

had to included the Canadian Pontiacs for this publication for the Canada otherwise the ads wouldn't be effective

for the cost.

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 I like Geasers take on this, it makes the most sense to me.

I agree with Greaser as well. Growing up in this era and being a car guy since the cradle, I can honestly say I never say an American Pontiac until a family friend bought a used 65 Catalina from someone who moved to Cape Breton from the US. He didn't have it long because things started to go, first the water pump, later the fuel pump and he couldn't buy parts for it in Canada. Bear in mind, there was no such thing as Free Trade in those days, bringing things in from the US or anywhere else was a major deal. One publication to fit both markets to reduce costs makes sense.