July 17, 2017

Population Growth on the Fringe of Portland Metro’s Urban Growth Boundary


This article originally appeared in the June 26, 2017, edition of the Daily Journal of Commerce.

Throughout history, people have migrated to new areas seeking opportunity. The Oregon Trail is Oregon’s heritage, blazed by people who headed west seeking land and new possibilities. Today, the search for land and opportunity continues.  What does current data tell us about the present-day search for land and opportunity in Portland and surrounding areas?

Recent Census Bureau data reveals continuing migration. And while the Portland area offers economic opportunity, the search for land for housing now leads families to the far fringes of the Urban Growth Boundary (“Metro UGB”) and across the river into Washington.  The data reveals a shortage of residential land, with significant growth pushing to the fringes of the UGB and beyond. People continue to seek buildable land for single-family home construction and room for their families to roam, and are venturing significant distances to find it.

People are drawn to the economic opportunities in Portland’s urban core. Cities surrounding Portland can be grouped into three general categories: a) cities within ten miles of Portland, b) cities ten to 20 miles from Portland, and c) cities more than 20 miles from Portland. The data shows demand for single family housing is pushing farther from the urban center through time, as lot prices near the core increase and as buildable land and housing there becomes inaccessible.

Cities within 10 miles of Portland grew rapidly from the 1950s to 1970s; close to or exceeding 100% population growth in each 10-year census from 1950 to 1970. This growth spread from the urban core to the closest available land. The majority of those same cities now have less than 10% growth from 2010 – 2016. Cities located more than 10 but less than 20 miles from Portland generally showed strongest growth percentages from the 1970s to the 1990s. While growth percentages for these cities generally met or exceeded 100% population growth in each 10 year period from 1970 – 1990, the majority of these cities now also have less than 10% growth reported for 2010 – 2016. In stark contrast, the majority of sample cities located more than 20 miles from Portland, but still within a 30-mile commute, showed lower growth rates from the 1950s through 1990s.  Now, however, explosive growth rates are generally apparent, with percentage growth rate census data for 2010 – 2016 generally double that of the cities located 20 miles or less from Portland. The data supports concerns voiced by critics of the Metro UGB, who point to growth spilling over into Clark County (Washington) and land ever farther from Portland’s urban core.

Oregon adopted growth management legislation in 1973, and Metro’s’s UGB was approved by the state in 1980. The Metro UGB is a legal boundary separating urbanizable land from rural land and is intended to encourage efficient use of infrastructure and prevent urban expansion onto farm and forest lands. The boundaries of the UGB are designed to expand over time so that a 20 year supply of developable land is maintained. The UGB covers 25 cities (including the urban portions of Washington, Multnomah and Clackamas counties) and currently includes 259,000 acres.

Those in planning and related fields have studied the effects of Metro’s UGB on urban development patterns for years. One 2003 article, “The Effects of Portland’s Urban Growth Boundary on Urban Development Patterns and Commuting” (Myung-Jin Jun, June 2003), concluded that Metro’s UGB has not effectively slowed suburbanization. Suburbanization results as people continue to seek land available for single-family development at the fringes of areas where the supply has been exhausted or become inaccessible.  Critics argue that supporters of the Metro UGB only analyze building permits and density changes for the specific Oregon counties on which the UGB is drawn, and ignore spillover growth into exurban counties in Oregon and Clark County, Washington (the Metro UGB does not extend north of the Columbia River). While a variety of factors complicate the analysis, many researchers conclude that the UGB has not effectively slowed suburbanization. The 2003 Myung-Jin Jun article reviewed 1990s data that pointed to a “significant level of spillover from the counties in Oregon to Clark County” in Washington. Sixteen years ago, Bae (2001) also analyzed cross-border impacts of the UGB between Portland and Clark County, Washington. Bae concluded that Portland’s growth management policies do not stop growth, but instead merely divert growth into other locations— for example, Clark County, which serves as a “safety valve” for growth outside the Metro UGB.

New census data indicates the spillover is continuing. In 2016, Clark County was one of the fastest growing counties in Washington State, with a 2.03% population increase of 9,190 residents (2016). This contrasts with growth rates in neighboring counties of .55% (Cowlitz); .61% (Skamania); and .30% (Lewis).  The City of Ridgefield, located in the current growth fringe range approximately 25 miles from Portland, led Clark County jurisdictions with a growth percentage of 47.4% from 2010 to 2016.

The growth pattern constitutes a new “Oregon Trail” of sorts, consisting of families moving outside or to the very fringes of the Metro UGB for single-family housing. This conclusion is supported by data published by the Southwest Washington Regional Transportation Council (“RTC”), which shows that the southbound morning and northbound evening commutes for those living in Washington and working in Portland’s urban core continue to increase. And highway traffic congestion between Clark County and the Portland Metro continues to increase. In 2015, over 294,000 vehicles crossed the I-5 and I-205 bridges on an average day, up from 273,000 in 2011. The commute corridor between Portland and Vancouver is characterized as one of the most highly congested in the nation, with a 291% increase in morning travel time on I-5 South in the five years preceding RTC’s 2016 report. As commuters attempt to shift their commutes away from the peak periods, rush hour congestion spans ever increasing time periods. Given the social and economic realities associated with commutes into and out of the urban core, it is hard to imagine any other explanation for the new Oregon Trail trend: many families simply have no other choice for traditional single-family housing.

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