Yes Virginia, Density Causes Sprawl—Lorax Edition

Among  all the wonderous myths of the density NIMBYs, surely “density causes sprawl” is king. Long ago Yogi Berra, of all people, nailed the illogic of that argument with his famous quip that “Nobody goes there anymore. It’s too crowded.”  (Mr. Berra also coined “it’s deja vu all over again,” a sentiment that seems all too fitting for another density post on this blog, but hey, it’s been a while.)

Like most specious myths, there is a grain of underlying truth upon which the broken ediface is built. Because yes, from the dawn of cities to the present, those with the means sometimes choose to escape the ills of the crowded city to find more favorable living conditions on the fringe.

But that is not the operative dynamic in a growing city like Seattle. Here, people opt for the fringe because they don’t have the means to afford Seattle. And that’s because demand for housing is high in Seattle, which is because there’s limited supply, which is because Seattle isn’t dense enough.

Yet somehow the myth persists that all those new, big, scary multifamily buildings filling up with people are actually driving people out of the city and increasing sprawl. Never mind considering where all those people would have gone to live if there were no new, big, scary multifamily buildings for them to move into.

There’s also a corollary myth regarding tree cover—that taking out trees to make way for new development creates sprawl because no one wants to live in a city that doesn’t have enough trees. Except, of course, all the people who are moving in to that new development that took out the trees. Pesky details.

But here’s the punchline of the post: the source of the tree corollary appears to be none other than the public servants of the City of Seattle itself. The City’s 2007 Urban Forest Management Plan states that,

Accommodating growth is important in order to preserve open spaces outside of the city. However, the loss of treed relief in our built environment reduces livability and further motivates sprawl.

and also that,

As the pressure to redevelop land within Seattle continues and the region’s population increases, density goals and development pressures need to be balanced with tree protection and planting goals. Finding the right balance is crucial to maintaining the city’s livability and encouraging new development within already developed areas rather than pushing it to the metropolitan fringe.

It sounds reasonable on the surface, and yes, trees are important for livability. But poke below that surface and say hello to bald-faced illogic: We must hold back development to prevent the loss of trees and preserve livability so that we can accommodate dense development that will cause loss of trees. Capiche?

And here’s another fun irony: If Seattle invests in expanding tree cover, it’s only going to make the City even more desirable. And that will further raise housing prices—a true generator of sprawl—and also increase development pressure.

What’s needed is some perspective. We all agree that trees have significant value on many levels. But if, for example, we think trees are important for carbon sequestration, we must consider how that fits into the big picture. The Urban Forest Management Plan estimates that Seattle’s existing trees sequester 52,400 Mg CO2/yr. How much is that? It’s 0.8 percent of Seattle’s total carbon footprint.  

But we also know that as density goes up, driving—and the associated carbon emissions—goes down. Just a two percent decrease in road transportation emissions would offset the sequestration provided by all of Seattle’s existing trees.

Same goes for stormwater management. The Plan places a $21 million stormwater mitigation value on Seattle’s existing trees. How does that compare to other mitigation strategies that can be integrated with dense development such as green roofs? And what about the impervious surface that is avoided with dense infill development—how much does that save us in terms of runoff pollution to Puget Sound, for example?

The list goes on. But the point is that planning decisions must be based on defensible analysis.  Does Seattle’s 30 percent tree cover goal meet that requirement?


Whether it’s about trees, ugly buildings, traffic, etc, there appears to be a fantasy scenario being invented in the minds of density NIMBYs in which people are fleeing Seattle because of all the terrible development that’s been happening.  But they’re doing no such thing. Plenty of people still want to live in Seattle—that’s why housing is so expensive here. 

Take Belltown, for example, often maligned for growing too rapidly without providing sufficient open space and schools. But somehow rents are still among the highest in Seattle. Maybe we should ask the people who choose to pay those rents whether or not the neighborhood is a success. And again, we’re faced with the gotcha: add more open space to Belltown and rents are going to go even higher (you may be feeling the pull toward a discussion of affordable housing, but we’re not going there now) .

None of this is to say that “livability” isn’t a critical ingredient of urban density (file under stupid-simple). Density advocates have expended an enormous amount of energy articulating their vision for how density can be livable, while at the same time helping us become more sustainable. If some folks disagree, that’s fine. But that disagreement is empty rhetoric if it isn’t backed with a credible alternative vision and plan. I’m still waiting.