Why Labour Day instead of May Day?

I am curious as to why we in Canada recognize worker’s rights and the labour movement on Labour Day instead of recognizing International Workers’ Day on May 1st, like much of the world.

Being in long weekend mode, my research on the topic is pretty cursory and involves mostly a Wikipedia entries that explain that John A. McDonald recognized union rights after a September 3rd protest, with Labour Day officially declared in 1894.

I’m sure a more complete history could be fascinating, and I may research it on a less sunny Labour Day weekend in the future.