South America the Darién watershed along the Colombia–Panama border, although some may consider the border instead to be the Panama Canal. Geopolitically and geographically all of Panama – including the segment east of the Panama Canal in the isthmus – is typically included in North America alone and among the countries of Central America. Almost all of mainland South America sits on the South American Plate. South America is home to the world's highest uninterrupted waterfall, Angel Falls in Venezuela; the highest single drop waterfall Kaieteur Falls in Guyana; the largest river (by volume), the Amazon River; the longest mountain range, the
American Falls to the north. To survey the rockfall and determine how to prevent the falls from becoming a series of rapids, the U.S. Army Corps of Engineers blocked the flow of water over the American Falls from June to November 1969. Results conflict as to whether tourist attendance that season was higher or lower than normal. Attendance increases were likely due to the news the cataract was dried off; decreases in tourists could be attributed to people believing both cataracts (the American and Horseshoe Falls) were dewatered. By December 1969, water was flowing over the American Falls again. In the mid‑1970s,