As of April 1, 1984, Washington's population was estimated at 4,328,100, an increase of 43,000 over last year's population. This report provides data pertaining to the: official April 1, 1984 population and housing estimates for cities, towns, and counties and components of population change. The following special reports are also presented: "Managing a Random Survey: The Bellevue Experience" (Steven M. Cohn); "Use of Survey Data in Developing Office of Financial Management Housing Unit Estimates" (Thereas J. Lowe); "Persons of Spanish Origin in Washington State" (Julie L. Baker and Theresa J. Lowe); "The Military Population in Washington State" (Felix D'Allesandro); and "A Special Consideration in Improving Housing Unit Estimates: The Interaction Effect" (Theresa J. Lowe, William R. Myers, and Lawrence M. Weisser). Data were obtained from city and county officials, Armed Forces personnel at major bases in the State, housing directors of the colleges and universities, and various divisions of the Department of Social and Health Services. Tabular data cover: city, town, and county populations; 1980-84 housing units; 1984 housing units by structure type; 1980-83 population change by the Census Bureau's racial categories and for persons of Spanish origin; 1980 census counts and 1983 population estimates by racial categories, and for the Spanish origin population by county; population changes for 1910-1984; general fertility rate for 1930-1984; marriages and divorces/dissolutions for 1950-1984; annexations, incorporations, and other municipal boundary changes; and population distribution by selected age groups for 1980 and 1984. (NQA)