Other pages about the topic: Population
Important: If you are conducting a census at this time, please contact OFM at pop.annexations@ofm.wa.gov or 360-902-0599 for special COVID-19 census guidance.
Per RCW 35.13.260 and RCW 35A.14.700, jurisdictions must send annexation paperwork to the Office of Financial Management within 30 days of the annexation effective date. OFM approval is necessary for a city to qualify for revenues related to population.
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?
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.
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