Imagine travelling for nearly two years across plains, mountains, and forests and finally arriving at this setting, the mighty waters of the Columbia River emptying into the Pacific Ocean, with the sea stretching out to the horizon. That is what greeted Meriwether Lewis and William Clark in 1805 at on their legendary North American expedition that originated near St. Louis. Fort Astoria, founded nearby in 1811 by the American Fur Company, was the first US-owed settlement on the West Coast. The Astoria-Megler Bridge was added to this picture 155 years later, the final piece connecting Los Angeles to Olympia, Washington, via US Route 101. Water from seven states and two Canadian provinces flows through the Columbia, passing under the four-mile structure, the longest continuous truss bridge in North America.