Detailed Instructions: In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.
Q: The mouth of this river includes Baker Bay, Grays Bay, and Youngs Bay. Its early course takes a u-turn around the Selkirk Mountains to flow south, although it most notably flows west. Important points along this river include Kettle Falls and Celilo Falls and it was first called the River of the West by Spanish explorers. It also includes Sauvie Island and Miller Island, formerly known as Rock Island, the site of one of the many dams built on this river. It enters the Pacific Ocean near Astoria. For ten points, identify this river of the northwest U.S. that forms much of the Washington-Oregon border.
A:
Social Science