actually it marks the anniversary of confederation, something like your 4th of july...
[quote:aaf29]On June 20, 1868, a proclamation signed by the Governor General, Lord Monck, called upon all Her Majesty's loving subjects throughout Canada to join in the celebration of the anniversary of the formation of the union of the British North America provinces in a federation under the name of Canada on July 1st.
The July 1 holiday was established by statute in 1879, under the name Dominion Day.[/quote:aaf29]