The Pacific Northwest was one of the last areas to be accurately mapped by European and American cartographers. At various times mapmakers thought that it was near a Asian region called Ania, that California was an Island, or that a great inland sea took up much of the American west. When Lewis and Clark ventured westward, they had a clearer idea of the coastline, yet they were still taken by surprise when they encountered the Rocky anc Cascade mountain ranges.

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