I get the sense that a there’s a lot of hand-wringing around the Northwest about how  “newcomers” are changing our cities too fast.  It’s a reasonable concern—rapid change really is unsettling.  And given the relatively low birthrates in urban areas, compared with exurbs and rural areas, you’d expect that “newcomers” are the biggest reason that population is growing in the Northwest’s urban areas.

But surprisingly enough, the numbers tell a different story:  in the most urban counties of greater Seattle and greater Portland—King County and Multnomah County in particular—the bulk of the population growth since 2000 came from births.  (Or, more properly, it came from “natural increase”—the excess of births over deaths.) 

Seattle-Portland nat increase

It seems like a paradox:  urban counties have comparatively low birthrates, but births are the biggest contributor to population growth.  How is that possible?  Once again, the answer is a bit surprising:  urban counties simply aren’t growing that fast.

  • At least, not in percentage terms:  population growth in King County, for example has trailed statewide growth rates for almost two decades.  At this point, the problem of “runaway population growth” in Washington’s most urban county is something of a mirage:  King County’s growth has been a mere echo of growth statewide.

    I’m not arguing that King County and Multinomah County should be growing faster.  I just want to put the numbers in perspective:  at this point, when we talk about population growth in the Northwest’s most urban counties, we’re mostly talking about us — making room for the families who already live here.  That’s not the whole story, obviously, but it’s the largest part of it. 

    And here’s another thought: when you consider that much of the net inflow of residents comes from international migration—people moving to the Northwest from other parts of the world—northwest urban counties are drawing surprisingly few newcomers, on net, from other parts of the US.  This is apparently true for the Western US as a whole:  this recent look at US migration patterns shows that the Western US lost nearly as many residents to the Southeast as it gained from the Midwest and Northeast.

    For those of you who love charts (and I know who you are!!) here’s a look at population growth in King County, WA, from 2000 to the present.  Contrast the steady growth resulting from natural increase with the streaky growth from migration. Migration comes in waves—and since 2000, it’s been more of a ripple than a tsunami.  And also note that migration tends to follow the economic cycles:  when times were lean in 2002 and 2003, and people have a hard time finding jobs, King County lost more people than it gained. 

    Lastly, a caveat—these are all estimates.  They’re not firm counts.  For Portland counties, they come from the Portland State Population Research Center. For greater Seattle, they come from the Washington State Office of Financial Management.  Any errors in compilation or presentation are mine. Regardless, we’ll have to wait until after the 2010 census comes in to get a better sense of how close the estimates are to reality.