—Meriwether Lewis

(http://www.autoadmit.com/thread.php?thread_id=5538810&forum_id=2#47733094)

https://en.wikipedia.org/wiki/%C3%81lvar_N%C3%BA%C3%B1ez_Cabeza_de_Vaca

(http://www.autoadmit.com/thread.php?thread_id=5538810&forum_id=2#47737264)

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As a result of his expedition, the 1529 Diego Ribeiro world map outlined the East coast of North America almost perfectly.

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Francisco Vázquez de Coronado reached Quivira in central Kansas. Juan Rodríguez Cabrillo explored the western coastline of Alta California in 1542–1543. Vázquez de Coronado's 1540–1542 expedition began as a search for the fabled Cities of Gold, but after learning from natives in New Mexico of a large river to the west, he sent García López de Cárdenas to lead a small contingent to find it. With the guidance of Hopi Indians, Cárdenas and his men became the first outsiders to see the Grand Canyon.[38] However, Cárdenas was reportedly unimpressed with the canyon, assuming the width of the Colorado River at six feet (1.8 m) and estimating 300-foot-tall (91 m) rock formations to be the size of a person. After unsuccessfully attempting to descend to the river, they left the area, defeated by the difficult terrain and torrid weather.[39]

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Hernando de Soto (/də ˈsoʊtoʊ/;[4] Spanish: [eɾˈnando ðe ˈsoto]; c. 1497 – 21 May 1542) was a Spanish explorer and conquistador who was involved in expeditions in Nicaragua and the Yucatan Peninsula. He played an important role in Francisco Pizarro's conquest of the Inca Empire in Peru, but is best known for leading the first European expedition deep into the territory of the modern-day United States (through Florida, Georgia, Alabama, Mississippi, and most likely Arkansas).[5] [6]He is the first European documented as having crossed the Mississippi River.[7]

(http://www.autoadmit.com/thread.php?thread_id=5538810&forum_id=2#47737306)