Imagine traveling for nearly two years across plains, mountains, and forests and finally arriving at this setting, where the mighty Columbia River empties into the Pacific near present-day Astoria, Oregon. That is the sight that greeted explorers Meriwether Lewis and William Clark in 1805 at the culmination of their legendary 8,000-mile North American expedition that originated near St. Louis.

The expedition's success opened the way for further exploration and development of the Pacific Northwest and by 1811, Fort Astoria, the first US-owned settlement on the West Coast, was established. Oregon became the 33rd state in 1859. The Astoria-Megler Bridge opened in 1966, 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 4-mile structure, the longest continuous truss bridge in North America.