Visa Free? From United States > Shanghai > United States but have a layover in Canada

I am flying from The United states > layover in Canada > to Shanghai and my return route is Shanghai > Canada > United States

Does this qualify for free transit program?

Can I say my initial departure was from The United States (even though there was a layover in Canada) and stay 144 hours in Shanghai then say my destination is Canada (even thought this is a layover to the United States). Since there is no guideline on how long I need to stay in any of the areas?

Or conversely can I say my initial departure was Canada (where my layover was from the United states) and stay 144 hours in Shanghai and then say my final destination is the United States?

Thanks!