What direction does the Columbia River flow?
The Columbia River is the largest river in the Pacific Northwest and, with a length of 1,953 kilometers (1,214 miles), is the 15th longest in North America. From its source at Columbia Lake at an elevation of 809 meters (2,650 feet) in Canada's Selkirk Mountains it first flows northwestward through eastern British Columbia, then turns southward toward the United States. It crosses the US-Canadian border north of Spokane, Washington, then flows southward across central Washington where it is joined by the Snake River, which drains southeastern Washington, eastern Oregon, and southern Idaho. The Columbia then turns westward, forming the border between Washington and Oregon. It flows through the Columbia River Gorge in the Cascade Mountains and on to its mouth at the Pacific Ocean near Astoria, Oregon. The Columbia River and its tributaries form the dominant water system in the Pacific Northwest Region.
The "Channeled Scablands" in eastern Washington are the geologic record of the catastrophic prehistoric floods of Glacial Lake Missoula, which carved deep channels and deposited huge sandbars along parts of today's Columbia River valley.