From the Great Lakes Echo:

The combined parking lots of four Great Lakes states take up nearly 500 square miles, according to recent estimates by Purdue University.

That’s enough pavement to cover 30 percent of Green Bay in Lake Michigan, 40 percent of Saginaw Bay in Lake Huron or twice the surface of Isle Royale in Lake Superior.

It also contributes to one of the biggest threats to Great Lakes water quality: Urban runoff. Read more.