Eastern Washington is a region of the United States defined as that part of Washington state east of the Cascade Mountains. It is notable for, among other things:

• Central Washington University
• The Columbia River and the Grand Coulee Dam
• Eastern Washington University
• Gonzaga University
• Hanford Nuclear Reservation
• The Palouse: very fertile farmland; among its products are lentils and wheat
• Washington State University
• Whitman College
• The Yakima Valley: also very fertile farmland; amongs its products are apples, hops, wine grapes, pears, and cherries

There have been sporadic movements to create a 51st state out of Eastern Washington by splitting the current state down the Cascades, but proposals have rarely progressed out of the state legislature's committees. Recent proposals were made in 2005, 1999, and 1996. Proposed names for the new state have included Eastern Washington, Lincoln, and Columbia.

Compared to Western Washington, Eastern Washington has roughly twice the land area and one-third the population. The growth rate between the two is roughly the same.

Adams, Asotin, Benton, Chelan, Columbia, Douglas, Ferry, Franklin, Garfield, Grant, Kittitas, Klickitat, Lincoln, Okanogan, Pend Oreille, Spokane, Stevens, Walla Walla, Whitman, and Yakima Counties are in Eastern Washington.

Cities of note

• Clarkston
• Colfax
• Ellensburg
• Moses Lake
• Pullman
• Spokane
• Tri-Cities
• Walla Walla
• Wenatchee
• Yakima