The urban growth boundary -- established in 1979 as a way to reduce sprawl and encourage more compact growth -- is the framework around which other political decisions and compromises are made.

CNN: Polluted rivers stain Portland's image

"We're going to make better use of land that's already in the urban growth boundary, " Bragdon says.

CNN: Polluted rivers stain Portland's image

Metropolitan Portland's 1.5 million population is already putting pressure on housing needs within the urban growth boundary, and another 700, 000 people are expected to move to the area during the next 20 years.

CNN: Polluted rivers stain Portland's image