When the tropical vegetation of Mexico, Central America, and the West Indies is combined with the temperate products of the United States and Canada, very little in the way of vegetable products need be obtained from the outside world. Likewise, when the mineral products of this area, chiefly the United States and Canada, be pooled for a common industrial operation, an almost complete mineral independence is achieved. Geographically and industrially, therefore, the North American Continent comprises a natural unit. Canadians use approximately one gigajoule per capita per day, which approximates the 200,000 Kilogram calories per capita per day that Scott estimated as an asymptotic maximum for a high energy society.