The Canadian Shield, a vast expanse of ancient rock, is centered around which area?

The Canadian Shield covers a vast area of land. It starts in Eastern and Central Canada and then joins the Great Lakes in the United States to the Arctic Ocean. It is stated that it covers half of Canada and touches the northern parts of the United States, such as Michigan, Wisconsin, Ohio, New York, Minnesota and Pennsylvania. There are barely any inhabitants in areas touched by the Canadian Shield and produce is sparse, as it is an extremely cold climate and not an ideal place for growing plants. There is mining, but industry is also equally sparse. The Candian Shield is one of the oldest geographical shields on this planet.