Since 1945, the legal jurisdiction off the coasts of States has changed from being a 3 mile territorial sea to a series of bands of territorial sea, contiguous zone, exclusive economic zone, and continental shelf. The paper summarizes the historical development of these zones. Now that Canada has submitted its claim for continental shelves beyond the 200 nautical mile (NM) limit to the United Nations’ Commission on the Limits of the Continental Shelf (CLCS), the author calculates estimates for the size of Canada’s continental shelf beyond 200 NMs in both the Atlantic and Arctic Oceans and assesses the effect of the counter-claims by its neighboring States.