Well before Meriwether Lewis and William Clark's monumental journey from the mouth of the Columbia River, explorers were mapping what would soon become the western coast of the United States. British Capt. George Vancouver explored and mapped the Pacific coast in 1790-1792, and published an atlas with the first accurate maps of that region in 1798. The federal government started mapping with the creation of the U.S. Coast Survey (today known as the Coast and Geodetic Survey) in 1807. In addition to such government-sponsored expeditions, private trade missions were often the driving force behind geographic exploration. Robert Gray of Boston, on a fur-trading mission to China, commanded the first ship to travel around the world under the American flag (1787-1789). On his next voyage (1790-1793) he was the first to explore the Columbia River, which he named after his ship. American statesmen would later use Gray's...