The drainage area of the Great Lakes is equal to nearly one-tenth of the entire area of the United States; 58 percent of this area lies within the United States. The information in Table 3 affords a ready comparison of the land and water areas involved in the United States and Canada in the Great Lakes system. It will be noted that the total water surface is almost one-third of the entire drainage area and more than five-eighths of this water area is on the United States side of the international boundry. Throughout the history of the North American continent, the Great Lakes and the St. Lawrence River have formed a navigable water system of tremendous social and economic importance, extending from the interior of the continent to the Atlantic Ocean.