Migration to region hit historic levels during last decade

Many newcomers come from other Washington counties and California

A new Puget Sound Trends report shows growth from 2010–2020 was nearly as much as 1960–1980 combined. In-migration, fueled by a strong job market, drove more population growth from 2010 to 2020 than in any other decade since the 1960s.

Population change is made up of natural increase (births minus deaths) and net migration (people moving into an area minus people moving out). Since 1960, a net million and a half people have migrated to the region, according to estimates by the state Office of Financial Management (OFM). Net migration has contributed 56% of the region’s total population growth. Natural increase has added 1.2 million people and accounted for 44% of the growth.

Net migration is the primary driver behind population growth trends in the region. While growth from natural increase remains relatively stable from year to year, net migration is far more volatile, rising and falling in response to the strength of job opportunities and attractions in central Puget Sound relative to other places.

Components of Change by County

King County has experienced large shifts in migration over the years. From 2010 to 2020, 63% of the county’s growth was new people moving into the county. But in the period from 2000 to 2010, just 39% of the county’s growth was from new transplants.

Snohomish County also had about 63% of its growth from migration this decade, up from 45% in the years from 2000 to 2010. Kitsap County movers made up 59% of the population’s increase. Pierce County’s 53% in-migration rate was the lowest in the region, although the county added nearly the same total number of people as Snohomish.

Where People Are Moving From

Census Bureau data on county-to-county migration provides more detail about where people are moving from. The data come from the 2014–2018 American Community Survey, which asked where the person lived one year prior to filling out the questionnaire.

The highest number of transplants came from other counties within Washington state, followed by movers from California. The central Puget Sound region draws people from all over the world. As many people came from Asian countries as came from Texas, Oregon, and Arizona combined. European countries were a source of more new residents than Colorado.

OFM’s 2021 population estimates will be released next summer and will show how much the COVID-19 pandemic has affected the region’s migration patterns and natural change.

Read the latest Puget Sound Trends report for more on population change and migration.