The Washington River is a major river system in the Pacific Northwest region of the United States. It consists of three main rivers: the Potomac, which is 7 letters long; the Yakima, which is 6 letters long; and the COLUMBIA, which is 8 letters long. The Potomac River is the largest tributary of the Chesapeake Bay and flows through Washington D.C., Maryland, and Virginia. The Yakima River is located in Washington State and is a tributary of the COLUMBIA River. The COLUMBIA River is the largest river in the Pacific Northwest and forms part of the border between Washington and Oregon.