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PSU’s Population Research Center releases new Oregon population estimates
Author: Risa Proehl, Population Research Center
Posted: November 16, 2011

Oregon’s population increased from 3,837,300 in 2010 to 3,856,815 in 2011, or by 19,515, according to the latest preliminary July 1 population estimates released by Portland State University’s Population Research Center (PRC). The magnitude of increase, one-half of one percent, is about the same as experienced last year. This year marks the fifth straight year of low population growth and represents the slowest growth since the 1980s. Average population growth in Oregon during the 2000s was about 41,000 per year, with the larger increases occurring during the early and mid-part of the decade.

Population growth consists of two factors: natural increase (the number of births minus the number of deaths) and net migration (movers-in minus movers-out). Although the state’s natural increase has been declining slightly since 2008, it has become a dominant force in adding to Oregon’s population. This year, two-thirds of Oregon’s population growth was attributed to natural increase and only one-third to net migration. Prior to 2009 and including the 1990s, the opposite was true and net migration accounted for most of Oregon’s annual population growth, and natural increase contributed only one-quarter to one-third of Oregon’s annual population growth. From 2010 to 2011, about 13,000 persons were added to the State population because of the natural increase (1,700 fewer than last year), and 6,500 residents were added due to a net in-flow of movers (about the same as last year). 

Recent statewide data show a decrease in school enrollment, federal and state tax exemptions, and the number of driver's license holders, but an increase in the number of Medicare enrollees, the number of driver's licenses surrendered from out-of-state, employed persons, and registered voters. The number of building permits for new housing was about the same as in the previous year.

Oregon’s larger metropolitan areas continued to experience the greatest population gains and accounted for almost three-quarters of the state’s overall population change from July 1, 2010 to July 1, 2011. Washington and Multnomah counties each added over 5,000 persons; Marion, Clackamas, and Deschutes counties each increased by around 1,000 to 2,200 persons. Oregon’s remaining counties each experienced population growth of less than 700 persons.

Although half of Oregon’s counties saw little population change in the past year, several counties are estimated to have experienced slight decreases (200 or less). The population losses in these counties, however, are attributed to a natural decrease, as the number of deaths exceeded the number of births. In better economic times when it is easier for people to move around, net in-migration offsets the natural decrease so that most of these counties experience overall population increases.

Oregon’s incorporated cities have gained an estimated 9,000 from 2010 to 2011, with a combined 2011 total of 2,682,400. Incorporated cities capture about 70 percent of the state’s population, about the same as in the last few years. Preliminary estimates also show that cities accounted for 46 percent of Oregon’s population increase, also about the same percentage than last year. Approximately 17 percent of the increase in Oregon’s city/town population was due to annexations, which is higher than last year (9 percent). 

PRC’s estimates also show population increases in 120 of Oregon’s 242 incorporated cities from July 1, 2010 to June 30, 2011. Portland added the greatest number of persons, increasing its population by over 2,000, followed by Beaverton (+900) and The Dalles (+800). The increase in The Dalles, however, was due to annexations during the year rather than to natural increase of net in-migration (as in the case of Portland and Beaverton).

Most cities in Oregon have seen much smaller increases this past year than in previous years. Cities showing a significant increase in population are likely explained by the occurrence of annexations, or a better accounting of their housing unit inventory and of the number of persons residing in group quarters facilities.

According to annual data submitted to PRC by Oregon’s cities, there have been some decreases this year in the number of persons residing in group quarters facilities such as senior care housing and student housing. The economy could provide an explanation. While college enrollments are up, perhaps some students might be doubling up in off-campus housing or are remaining at home with their parents to save money; and with the high expense of residing in a decent care facility, families could be finding alternate means of caring for elderly family members at home. 

PRC produces annual population estimates for Oregon, and its counties and incorporated cities using the most recent available data. These estimates are based on changes in the number of housing units, persons residing in group quarter facilities, births and deaths, students enrolled in public school, persons in the labor force, Medicare enrollees, State and Federal tax exemptions, Oregon driver's license holders, and other administrative data. Statewide housing and group quarters population data for are collected from annual questionnaires are sent directly to Oregon’s cities and counties. If we do not receive updated annual data from a city, its population estimate remains the same as the previous year. The annual population estimates are used in revenue distribution to local governments and in program administration.

The preliminary population estimates are subject to revision during a one-month review period. The final July 1, 2011 population estimates will be certified on December 15, 2011. The annual population estimates are revised quarterly to account for annexations throughout the year.

The preliminary population estimates can be found on PRC’s web site at: