Does a UGB cause density?
Oregon land use law favors places that have a variety of development types — apartments, condos and single-family homes, office buildings big and small, large factories and small manufacturers. The fact is, UGB or not, any city's going to have a healthy share of multifamily housing. But Oregonians familiar with other parts of the country, know apartments in other cities tend to wind up nestled on six-lane boulevards on the edges of town, surrounded by parking lots. The purpose of UGB's is to encourage that multifamily development to be within existing business districts, where people can walk to get to what they need and support small businesses.
The statewide planning goals encourage a city to offer a variety of housing options that are located near other city services and amenities.
Does a UGB cause rents and house prices to go up?
No matter where you are in the country, new housing is expensive. The average new American house costs more than $400,000, according to the National Home Builders Association. Rents in Portland aren't that different from Austin, Denver or Atlanta. There's a combination of factors at play: Housing construction almost totally stalled during the Great Recession, but population growth didn't. Once the recovery began, the rush to build new housing caused the prices on everything from labor to drywall to go up.
In greater Portland, one driver of rising housing costs are "system development charges" — fees that builders pay to help support construction of the pipes, roads, parks and schools that are required for urban living. Taxpayers here have said those bills should be picked up by people buying new housing, not the public at large.
So where a new sewer line in, say, Phoenix, can be paid for by a combination of a small sales tax and small systems charge, here, all of those charges are put back on the developer, and ultimately, home buyer or renter.
Certainly, the urban growth boundary does cause land values to go up a bit. But compared to the totality of home prices, the difference is minimal: For a 5,000 square foot lot, the difference between land selling for $100,000 per acre and $200,000 per acre is about $11,500. When you're talking about $450,000 houses — an $11,500 increase in land price is not causing affordability issues.
What's the point in having a boundary if it can be expanded indefinitely?
The UGB is meant to make the region think about growth, not to stop it completely. By encouraging developers to think about areas already in the UGB but available for development, it slows the rate that farms are converted to housing and prevents leap-frog developments.
Reference: UGB 101: Everything you wanted to know about the urban growth boundary but were afraid to ask, Portland Tribune, Nick Christensen, Metro, January 2018.