–Young adults have long been over-represented in the King County population.
–The Millennial generation is dominating population in King County even more than their parents’ generation.
Change of population age structure in King County
The pattern of age distribution in the Seattle area reflects the pattern of in-migration. Migration into King County is heavily from other states or foreign countries, and migration over long distances leans largely toward young adults. Nearly 50 percent of migrants to King County are between 20 and 35 years old (Millennials) and only 8 percent are between 55 and 75 (Boomers).
We can see all this unfold through population pyramids, a favorite tool demographers use to illustrate the distribution of population across age groups and gender. Figure 1 shows the population pyramid for the entire United States in 2018. By convention, males are on the left, females on the right. Each bar represents the number of people in that five-year age group.
The remnants of the Baby Boom shows up as a slight bulge in the 55 to 59 age group, but mortality and large scale immigration of post-boomer aged people has diluted that bulge considerably. The Millennials show up as the bulge in three bars between 20 and 34. The smaller Gen-X cohort is seen in the shorter bar between 40 and 44, and their smaller cohort of children is toward the bottom.
Figure 2 shows the pyramid for King County in 2018. Totally different shape. The Boomers near the top are shrinking away, while the Millennials have bulged way out, especially in the two bars between 25 and 34. The Seattle area has always been different than the country as a whole, since it attracts large numbers of in-migrants, and in-migrants tend to be young adults. And older cohorts diminish more rapidly in places like Seattle as retirees move to warmer places. So, some difference from the national picture is expected.
The 2018 pattern is a more extreme version of the past. Figure 3 shows the pyramid from 1990, when Boeing was decidedly middle aged and young talent was just starting to arrive in large numbers to Microsoft. Newsweek magazine had a cover story titled “Everyone is Moving to Seattle.” The Baby Boom bulge is quite pronounced, and since the younger boomers were still in prime age for migration, that bulge was expanding. Millennials were about two-thirds of the way onto the planet. The older, “Greatest” generation was quite a bit smaller.
Figure 4 shows the pyramid for 2000, after the go-go decade of the 1990s. The Boomers continue to dominate the picture, and the Millennial cohort is still quite a bit smaller. Gen-X is in prime migration age at this point and beginning to fill in the post-Boomer bars in the 25 to 35 range.
In 2010, things start to change. The Millennials, the oldest of whom are now in the 25 to 29 bracket, are starting to make their presence felt. Amazon is just starting to bulk up, and recruits to the area are mostly of the Millennial cohort. The Boomers are still a significant presence, the oldest of whom are just hitting retirement age at this point.
What happens between 2010 and 2018 is quite dramatic. Figure 6 compares the shapes of the 2010 and 2018 pyramids. In just eight years, the young adult bars shoot out. The Boomer bars would have advanced up the pyramid to about two spaces, so they shrink quite a bit.
How big were the shifts? Figure 7 shows the population change, in numbers of people, by age group (both genders) in just five years. (This chart uses the more accurate 5-year average data from the American Community Survey, so it understates the most recent changes.) The chart shows the growth of each cohort from 2012 to 2017, with total population growth shown on the far right.
The change is significant. The three bars for the Millennial cohort as they stood in 2012 (15 to 29) all grew faster than the county as a whole. The Gen-X groups all grew slower than the county average, and all age groups above age 45 got smaller.
Exaggerated impact of Millennial generation
This general pattern is explainable through the normal shifts in population, although the Millennial growth is exaggerated. People migrate mostly when they are young adults, and migrants to an expensive region like Seattle usually have a job before they arrive. The rapid hiring by Amazon explains a good deal of the Millennial bulge.
At the other end of the age spectrum, few older people migrate to a rainy, expensive place like King County, and some older King County residents will migrate out to warmer, quieter, less expensive places. And within the older groups, mortality begins to take a toll. About two thirds of the decline in the Boomer groups can be attributed to deaths, and one third to out-migration.
Growth in the Millennial population of King County is much higher than the average across the country. A strong technology job market attracts young adults, and an expansive policy toward apartment building keeps rents from climbing as they have in Northern California.
Questions going forward are:
- Will they stay, or, as recent research suggests, return in large numbers to their hometowns.
- Will Seattle remain a “sticky” place where people “come for the job, stay for the lifestyle?”
- Will the Millennials who stay in the region (having been born here or moving here), have their own children in large numbers?
- Can the region’s supply of single family homes expand to meet the needs of growing Millennial families?