North America's largest sub-tropical wilderness reserve is a UNESCO World Heritage Site, but one that is threatened, and so it was added to the list for 'in danger' world heritage sites nine years ago. For thousands of years, water flowed south from Lake Okeechobee and into the "River of Grass." From the late 1800s well into the 1900s, business interests with government cooperation sought to drain the Everglades so land could be developed.