It is a statutory holiday in most of Canada today, usually called something banal like "civic holiday"; it is simply a way to give Canadians an extra long weekend in our extra-short summers. In Toronto, they call it Simcoe Day, in honour of John Graves Simcoe, Lieutenant Governor of Upper Canada (now Ontario) in the 1790s.
Simcoe did a great deal, but his most lasting legacy is a lesson in the power of planning and design, and how it can influence history.
Simcoe had to deal with an influx of United Empire Loyalists who had to (or wanted to) leave the United States after the American Revolution. However he was also worried about the province being overrun by Americans, and wanted to attract other settlers from Britain. So he had his surveyors lay out a vast super-grid across the province that is remarkably accurate; you can be driving north on a country road and have to jog a bit at an intersection; this is an adjustment for the curvature of the earth, to keep the lines from converging as you go towards the North Pole.
An immigrant receiving a land grant had to clear the road on all four sides within a period of time to get title to the land. Ontario got a grid of lines and concessions that made transport of agricultural and then industrial goods easier than anywhere else in the country. The province became the Canadian industrial and agricultural powerhouse because of a planning and design decision made in 1795.
In Quebec, they relied on rivers for transport well into the 20th century. Land was divided according to the Seigneurial system, based on thin strips of land leading to the water. These would get thinner and thinner as they were subdivided for inheritances; the rest of the province was considered one big woodlot. Many believe that this was a major cause of economic development lagging considerably behind Ontario; there was really no way to get around.
It's hard to imagine that decisions made in 1795 affect us today, but planning and urban design is like that; the decisions we make can have repercussions for centuries.