The greater metro Portland, Oregon, straddles two states, offering an intriguing natural experiment for gauging the effects of different growth management laws. The Oregon side operates under the nation’s oldest and most mature growth management system, while the Washington side is governed by a newer law.

On paper, the growth management programs share many features. Yet in practice, their records have produced startlingly different results: Over the last two decades, Clark County, Washington, accounted for the large majority of all rural and exurban housing and population growth in the greater Portland area.

Sightline’s report, Rural Sprawl in Metropolitan Portland, examines trends in Portland-area development using census data from the last two decades. Two maps clearly reveal how the lion’s share of rural sprawl has occurred across the Washington border.

Rural Sprawl in Metropolitan Portland

See map of Portland-area growth 1990-2000

See map of Portland-area growth 2000-2010

July 18, 2012