RCW 43.62.030 states that the Office of Financial Management shall annually determine the April 1 populations of all cities and towns of the state. OFM population estimates for cities and towns are used in state program administration and in the allocation of selected state revenues (RCW 43.62.020). Population estimates for counties are used to allocate revenues as specified in RCW 36.13.100 and RCW 43.62.030.

Intercensal estimates

Intercensal estimates are estimates that are bracketed on both sides by decennial census or state-certified special census counts. As such, they yield a more consistent series than postcensal estimates which only reference the prior census point. (Last updated March 21, 2024)

The purpose of this site is to provide a convenient location where federal and state agencies, local governments, organizations, and members of the public can obtain information about annexations. State agencies that use this site include WSDOT Geographic Services, DOR Tax Payer Account Administration, and DOR Property Tax Division.

Posting on this website does not replace reporting to DOR by counties and cities. RCW requirements are still in effect.

Why does my city need Office of Financial Management (OFM) approval for an annexation?

State law, RCW 35.13.260 and RCW 35A.14.700, requires that annexation certificates be approved by OFM before the population and housing in an annexed area can be used for population purposes. All annexations and boundary line adjustments must have a certificate sent to OFM even if there is no population in the area.

Which documents do I need to send to OFM?

1. Census 2020
2. Census 2010
3. Census 2000
4. Census 1990

The American Community Survey (ACS) is an ongoing survey of the nation's population that provides detailed demographic, housing, social, and economic data—data that used to be collected via the decennial census long form.

Click on a tab below to access various 2010 Census data products.

These Detailed Demographic Profiles are based exclusively on Census 2000 Summary File 3 (SF3) data, which consists of 813 detailed tables of Census 2000 social, economic and housing characteristics compiled from a sample of approximately 19 million housing units (about 1 in 6 households) that received the Census 2000 long-form questionnaire.

Population and housing characteristics

This table is a compilation of data from several Summary File 3 tables. Items include Group Quarters Population, Housing Unit Population by Tenure and Structure Type, Average Household Size by Tenure, Housing Unit Occupancy Status, and Occupied Housing Units by Tenure and Structure Type. Each component of this data table is described separately below.