Rock Island is a city in Douglas County, Washington, United States. It is part of the Wenatchee–East Wenatchee Metropolitan Statistical Area. The population was 788 at the 2010 census.
Rock Island was officially incorporated on November 3, 1930. The area of Rock Island was used by Native American tribes for fishing and crossing of the Columbia River due to the nearby Rock Island Rapids prior to settlement of the Washington Territory.
The site had been previously settled in the late 19th Century and was known as Hammond; early maps sometimes show the city as Hammond P.O. (Post Office) or Power City. In the teacup valley in which Rock Island is currently located, two men, Ingraham and McBride, opened a trading post in the early 1860s. Their patrons were local Native Americans, who often fished that stretch of the Columbia when the fish were running. The two pioneering men would later move their post to the mouth of the Wenatchee River, leaving little trace of their stay.
The most notable figure in Rock Island's founding is James E. Keane. As the first permanent settler to the Rock Island area, James Keane arrived with a crew of men in 1887.