Washington: Total housing units NOTE: These ACS data are estimates based on a five-year average, meaning that data gathered from 2017, 2018, 2019, 2020, and 2021 are averaged together to come up with the results shown here. There is no problem with comparing these data to census data from 2000. For a technical discussion of the "margins of error" associated with ACS estimates, please see: (https://www.census.gov/programs-surveys/acs/library/handbooks/researchers.html) Source: 1980, 1990: U.S. Bureau of the Census, Census of Population and Housing, (https://www.census.gov/programs-surveys/decennial-census/data/tables.1980.html); 2000-2020: U.S. Bureau of the Census, Explore Census Data, (https://data.census.gov/cedsci/advanced); DATE LAST UPDATED: December 13, 2022.