By looking at a map of North America, it is often hard to appreciate just how important the Great Lakes are. But, when we begin to look at some of the statistics, it easy to see that the Great Lakes are an important part of the region in which they are located. If you placed all five of the Great lakes together, and measured the area that they covered, you would discover that the Great Lakes would cover more than 94,00 square miles! Of the five Great Lakes, Lake Superior is the largest; you could actually place all of the water from the other lakes into Lake Superior and Lake Superior would never overflow! As a water system though, the Great Lakes are the second largest supply of fresh water comprising over 21% of the world's fresh water supply. Only the polar ice caps contain more fresh water than the Great Lakes. Of the five Great Lakes, there is only one that is located, entirely, in the United States- Lake Michigan.
Due to the fact that the Great Lakes cover such a large area, the climate is different in different areas. While the northern part is very cold and the area is covered by dense forests, the southern area is warmer and is much more urban. These differences also imply that there are different concerns in the different regions because the Great Lakes are used differently by the people in each region. One example of this is Lake Superior. Due to the cool climate, poor soils, dense forests, and sparse population, there is only a minimal amount of pollution that enters Lake Superior each year. Where as Lake Erie is the most polluted of the five Great Lakes due to it's small volume and the rich soil which creates many agricultural opportunities.