Welcome to Science - The Grand Canyon was created by the Colorado River over a period of 6 million years.
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Lewis and Clark

The addition of the Louisiana Purchase Lands (828,000 square miles), nearly doubled the size of the United States at that time. President Jefferson sent Lewis and Clark on an expedition to the west to learn everything possible about the land, the Native Americans and their customs, plants, animals, birds minerals, streams and their navigable possibilities. The explorers left on May 14, 1804 and returned to St. Louis on September 23, 1806.