Chinook is the name given to multiple groups of Native Americans who share a common history of speaking one of the three main Chinookian languages. Now numbering about 2,000 members, the nation of Chinook Indians is predominately based in Oregon and Washington in the northwest corner of the continental United States. The Chinooks history with Westerners dates back to 1805, being described by members of the Lewis and Clark Expedition, but they had been known to traders in that region for more than a decade prior to that. When first encountered by Lewis and Clark, the Chinook nation was thought to be much smaller than it actually was. Initially, the Chinooks were numbered at about 400. That did not take into account numerous groups of Chinooks spread about the Columbia River in what would become the northwest United States and southwest Canada.