State Lines, Stark Contrasts: Report Charts Rural Sprawl in Greater Portland

A new report from Sightline Institute explores the spread and prevalence of rural sprawl in the Portland region. The conclusion: clear evidence of the impact of wise land use planning, with rural sprawl far more widespread in Clark County, Washington, than in Oregon's share of the metro region.

Because it straddles a state border, the Portland region provides an unique opportunity to examine the impacts of different planning programs in each state. Oregon first adopted statewide land use planning in 1973, and the Oregon side of the region adopted an urban growth boundary in 1979. Although the boundary has been shifted several times since that time, well over 90 percent of residential development since then has occurred within the original boundary.

Clark County, meanwhile, adopted growth management laws much later than Oregon--not until the mid-1990s, with a substantial amount of growth "grandfathered in."

The results are clear in the patterns of development on the ground. In the period Sightline examines, from 1990 to 2010, Clark County saw substantially greater exurban housing development, even after its growth management laws were enacted. Although the county accounted for less than 30 percent of the region's overall housing growth from 2000 to 2010, over 60 percent of new exurban homes were built there. (See map at right, in which each red dot indicates 10 new people living outside an established urban growth area.)

During that decade, Multnomah County added more new houses than Clark County, and Washington County, Oregon, added more new residents. But the study notes that "only a tiny share of their new housing [occurred] outside the urban growth boundary." That is abundantly clear from Sightline's map at right.

Sightline concludes: "The contrasting records of the Oregon and Washington sides of the Portland metro area offer a clear lesson: rural sprawl results from policy choices. Differences in how land use and zoning policies are designed and enforced--rather than differences in demand for new housing per se--lie at the heart of the different housing and population trends in Greater Portland."

This study is clear evidence that Oregon's land use planning laws have helped stem a tide of sprawling, expensive development that could have destroyed thousands of acres of productive farmland, marred scenic landscapes, and clogged rural roads. Rural sprawl is a particularly insidious and expensive kind of development. It is typically less visible than suburban subdivisions, but requires great expenditures to service and causes unique harm to the environment and working landscapes. By reducing the spread of rural sprawl, Oregon has reduced conflicts between farms and houses, helped preserve clean air and water, and reduced congestion on rural roads.

But the study's emphasis on policy choices reminds us that our leaders need to hold firm to their commitment to prevent rural sprawl and create great neighborhoods in our existing communities. Once again, Oregon shows itself as a beacon for a better balance of development and conservation. 1000 Friends will continue working to make sure we stay that way.

Learn more about the role of land use planning in your life and community at

Download the report and full-size maps from Sightline here.