Washington is an aging state.
This is part of a broader trend happening across the nation: The median age in the U.S. jumped from 37.2 in 2010 to 38.8 in 2020, census data showed.
And new data shows that in Washington, the median age has gone up in all 39 of the state's counties since 2010. At the same time, the number of people 65 and older has increased sharply, while the number of children under 5 has declined.
Statewide, the median age increased by more than one year over the past decade, rising from 37.3 in 2010 to 38.6 in 2022, according to data from the Washington Office of Financial Management. The median represents the midway point — in other words, half the population is older and half is younger.
In some of Washington's counties, this demographic trend is particularly striking.
In Jefferson County, which is easily the oldest county in the state, the median age increased by nearly 7 years, hitting 60.7. Port Townsend, the county's only incorporated city, has become a popular destination for retirees, which has surely contributed to the rising median age.
In fact, Jefferson is among the oldest counties in the U.S. The nation's oldest county, according to census data, is Sumter County, Florida, which had a median age of 68.4 in 2021. Jefferson County ranked sixth oldest.
Three other Western Washington counties have also seen significant jumps in the median age since 2010: Pacific increased by six years, and San Juan and Clallam were both up by nearly five.
Jefferson, San Juan and Clallam are among the nine counties in Washington with a median age higher than 50.
But if this demographic trend has escaped your notice, it could be because you live in King County. The median age here has had the smallest increase in the state, up from 37.1 in 2010 to 37.3 in 2022 — the eighth lowest among the state's 39 counties. This is likely due to the constant influx of young adults in the Seattle area over the 2010s.
Unlike King County, most parts of the state haven't had an infusion of young people to help offset the aging of the massive baby boom generation.
As more boomers — people born between 1946 and 1964 — celebrated their 65th birthday each year, the share of Washington's population 65 and over has grown much faster than the overall growth rate.
Washington's 65-and-older population increased by a whopping 63%, from about 828,000 in 2010 to 1.35 million in 2022. The overall population saw a 17% growth rate during this period.
In Clark County, where Vancouver is located, the 65-and-older population increased by nearly 85%. It was also up more than 80% in San Juan and Thurston Counties. In King County, the 65-and-older population increased by 53%, from 211,000 to 322,000.
While the number of older Washingtonians increased sharply, the number of very young people declined slightly. There were about 438,000 kids under age 5 in 2022, down by nearly 2,000 from 2010.
This is due, at least in part, to the larger demographic trend of young adults putting off marriage and having fewer kids. We see this reflected in declining fertility rates in much of the country. In Washington, there were 54.2 births per 1,000 women ages 15 to 44 in 2021, according to the National Center for Health Statistics. That's down from 63 births per 1,000 in 2005.
Thirteen Washington counties saw double-digit declines in the number of children under 5. In Yakima County, for example, the under-5 population fell by 14.5%, or about 3,100 kids.
There were, however, 10 counties where the population under 5 years increased modestly, including King, Pierce and Snohomish. Of the three, Snohomish had the largest increase, at 5.5%, or around 2,600 kids.
Whitman County, home to Washington State University, is the state's youngest county, mainly due to the large number of college students. The median age there is just 25.1 years.
There are four other counties with a median age lower than 35: Adams, Franklin, Yakima and Grant. In all four, Hispanic people make up a large share of the total population. Hispanic people are the youngest major racial or ethnic group in the U.S., while white people are the oldest, according to census data.