Americans are wont to say that we Canadians took our annual Thanksgiving tradition from them. In other words, we usurped, copied, stole it from them, if you will!
Yes. The North American Thanksgiving celebration has been – usurped, copied, stolen! They stole it from us!
Long before the discovery of North American continent celebrations of thanks for the harvests were common in Europe in the month of October.
The Americans attribute the first Thanksgiving on the continent to the Pilgrims in the early 17th Century (1621, actually). It is held in November long after the harvests actually begin!
In fact, the very first Thanksgiving was held in Newfoundland by the explorer Martin Frobisher in 1578 to give thanks for their safe voyage across the Atlantic. This was 43 years before the arrival of the Pilgrims!
The truth is, our Thanksgiving was originally in November as well. We changed it after World War One to avoid conflicting with Remberance Day on November 11th. Also our harvest season is earlier.
So we are willing to share the tradition with our southern neighbours. As long as they cease to arrogate it as their own!

Martin Frobisher in Newfoundland 1578

The Pilgrims arrival 1621 (43 years later!)