Washington is a city in Tazewell County, Illinois, United States. The population was 10,841 at the 2000 census. There are currently 13,167 people living in Washington, according to a 2004 special census. Washington is part of the Peoria Metropolitan Statistical Area. From April 2000 to 2006, Washington's population grew 23.3 percent, second in the Peoria area only to Germantown Hills.