Population growth is driven by two factors: net migration (people moving in minus people moving out) and natural increases (births minus deaths). Since 1960, most growth in Thurston County has been due to immigration. Between 2010 and 2015, an average of 2,320 people moved to Thurston County per year (68% of total growth). While much of this immigration was likely due to the relatively stable economy in Thurston County, it is likely that the increasing cost of living in the Seattle metropolitan area also played a role as individuals from the metropolitan area looked for ways to reduce escalating costs of living - particularly in housing.
Migration to Thurston County has increased from 758 new residents in 2010 to 4,329 new residents in 2015.