The Willamette River, stretching 187 miles through northwestern Oregon, is indeed a significant tributary of the Columbia River, contributing 12 to 15 percent of its flow. Originating near Eugene, the river flows northward, passing through important cities like Salem and Portland before joining the Columbia. The Willamette Valley, formed by the river and its tributaries, is a fertile agricultural hub and home to two-thirds of Oregon's population. This river has played a vital role in the region's history, from supporting indigenous tribes to being a key transportation route during the 19th century.