Population by age, mapped by county
Median Age, 2020
In 2010, the median age of persons living in Washington state was 37.3 years. In 2020 the median age had increased to 38.5 years.
Jefferson County had the highest median age in 2010 at 53.9 years. By 2020, the median age in Jefferson County had reached 59.5 years.
In 2010, Whitman County, home of Washington State University, had the state's lowest median age at 24.4 years. In 2020, Whitman County still had the lowest median age at 24.5 years. Adams County was the only other county in Washington state with a median age less than 30 years in both 2010 (29.0 years and in 2020 (26.7 years).
Percent of Population Age 65 and Above, 2020
The age 65 and older population generally represents those nearing retirement.
In 2010, 12.3% of Washington state residents were 65 or older. In 2020, 16.7% Washington state residents were 65 and older.
Jefferson County had the highest share of the population age 65 and older in Washington state with 26.3% in 2010 and 39.2% in 2020.
Franklin County had the lowest share of population 65 and older, with only 7.3% in 2010 and 9.9% in 2019. Whitman County has the second lowest percentage of population 65 and older, with 9.5% in 2010 and 10.0% in 2019.
Percent of Population Age 85 and Above, 2020
In 2010, 1.7% of Washington state residents were age 85 or older. In 2020, 1.8% of Washington state residents were age 85 or above.
Garfield County's had the hightest share of 85 and older population in 2010 with 4.2%.
Wahkiakum County had the highest share of 85 and older population in 2020 with 5.2%.
Franklin County had the lowest share of population 85 and in 2010 with 0.8%.
Adam County had the lowest share of population 85 and older in 2020 with 0.7%.