Over the last year or two I have heard statistics quoted about the Great Lakes, and how much of the Continental 48 States could be covered with the water within the lakes. I have heard that the lakes could cover the US to anywhere from 5 inches to 5 feet deep. Sometimes it is the entire Great Lakes, sometimes it is just Lake Superior that is mentioned. The numbers seem staggering to consider, and with the variability between the anecdotal references, I decided to do some math to find out what the real deal is.

To make some of the math easier, I will do the calculations in the Metric system, then convert at the end. Keep in mind that these calculations assume that the land area in question is completely flat – no mountains, hills or valleys. And, just in case any of my former math teachers are reading this blog, I am going to show my work.

The Great Lakes are enormous. If you don’t live in the Upper Midwest of the United States, or you have never visited the area, it may be hard to imagine their size. And they contain an enormous volume of water.

 I looked up the land area of the contiguous 48 United States (those in North America, excluding Alaska). The total land area is 8,080,464 square kilometers. Volume is area x depth, so to get to the depth, simply divide the volume by the area:

Converting to feet:

That means that the water in Lake Superior, by itself, could indeed cover the Contiguous 48 States to a depth of nearly 5 feet. Put another way, the water in Lake Superior could fill a swimming pool the size of the 48 states to 5 feet.

No matter how you think about it, that is a staggering number. If you include all of the Great Lakes you get the following:

Converting to feet:

Hopefully this clears up the truth and rumors about how much water is in the Great Lakes.