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Oregon -- Population -- Statistics, Demographic surveys -- Oregon, Population forecasting -- Oregon -- Polk County


Different parts of Polk County experience differing growth patterns. Local trends within the UGBs and the area outside them collectively influence population growth rates for the county as a whole.

Polk County’s total population has grown moderately since 2000, with an average annual growth rate just below two percent between 2000 and 2010 (Figure 1). However, some of its sub-areas experienced more rapid population growth. The Polk County portion of Salem-Keizer, the most populous UGB, posted an annual average growth rate of 2.8 percent, while both Independence and Monmouth saw average annual growth rates above those of the county, at 3.4 and 2.1 percent respectively, during the 2000 to 2010 period.

Polk County’s positive population growth in the 2000s was largely the result of substantial net in-migration, though a small natural increase contributed as well. While in 2000 Polk County’s total fertility rate (TFR) was below that of Oregon as a whole, the state’s rate dropped by 2010 while the county’s did not. Steady total fertility rates in the 2000s compared to the state average led to a relatively steady rate of natural increase during the 2000-2010 period. This has continued in recent years (2010-2015). While net in-migration far outweighed natural increase during the bulk of the last decade, as net in-migration has slowed the gap between these two components has diminished in recent years, thus slowing total population growth in the county (Figure 12).

Total population in Polk County as a whole and in its sub-areas will likely grow at a slightly faster pace in the near-term (2017 to 2035) compared to the long-term (Figure 1). The tapering of growth rates is largely driven by an aging population—a demographic trend which is expected to contribute towards a waning natural increase (more births than deaths). As natural increases lessens, population growth will become increasingly reliant on net in-migration.

Even so, Polk County’s total population is forecast to increase by more than 24,000 over the next 18 years (2017-2035) and by more than 68,000 over the entire 50 year forecast period (2017-2067). Sub-areas that showed strong population growth in the 2000s are expected to experience similar rates of population growth during the forecast period.


This report is published by the Population Research Center at Portland State University, and is a product of the Oregon Population Forecast Program.

The introductory presentation, preliminary forecast presentation, and Polk County final forecast tables are attached to this document as supplemental files.

Persistent Identifier

polk introductory presentation.pdf (2331 kB)
Introductory presentation

Polk_prelim_presentation.pdf (1553 kB)
Preliminary presentation

Polk_County_Final_Forecast_Tables.xlsx (132 kB)