The Ft. Clatsop National Memorial features a replica of the log fort built by Lewis and Clark in 1805 to provide winter quarters for their expedition that mapped the northwestern portion of the Louisiana Purchase.
The expedition was authorized by President Thomas Jefferson, who believed that there was a waterway that would provide a means of travel from St. Louis to the Pacific Coast. The mouth of the Columbia River had already been discovered by ship.
To really appreciate this historic area read the book Undaunted Courage by Stephen Ambrose.