Thanks for noticing Michael!
Pretty simple, really, if you understand the concept of the 4th of July in the USA.
July 1st 1867 was the date of the enactment of the British North America Act which united the colonies of Nova Scotia, New Brunswick and the Province of Canada (Ontario and Québec) into a federation of four provinces called the "Dominion of Canada". Essentially the birth of Canada as a country.
The term "Canada Day" is relatively new, as the date was originally "Dominion Day" until 1982 when the change was officially enacted by law.
In celebration, like you guys on July 4th, we take the day off work, drink a lot and then blow shit up.
Now that this history lesson is over, I've got some beer to down!
Mark