TRPC has been preparing forecasts of population, housing, and employment periodically since the late 1960s. These forecasts are used for many purposes, including:

• For local sewer, water, land use, school, and other planning purposes
• To develop the Thurston County Buildable Lands Report
• To identify future congestion concerns in TRPC’s travel demand models
• By the private sector for business planning

The most recent countywide forecasts were adopted by TRPC in March 2018. Small area forecasts (for cities, towns, fire districts, school districts, etc.) were adopted in 2019. Updates are available every three to five years.