Population

Marion and Polk counties

Marion and Polk counties lie in the central Willamette Valley, covering a total area of 1,938 square miles out to the western Coast Range, and up to Mt. Jefferson on the eastern side. The Willamette Valley is home to the greatest share of Oregon’s employment and population.

The Salem Metro Area (SMA) population has grown quite a bit over the past twenty years, surpassing the statewide growth rate (see Figure 1 in PDF file). Marion County’s population has grown at an annual average rate of 2% over the past 20 years, with 12.6% growth in the past decade. Polk County, which includes the western portion of Salem, added 6,765 residents between 1990 and 2010, growing 39.6% over the period. Oregon, by comparison, has had a lower growth rate of 35.2% during that time.

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Total Population by County

Marion County Polk County
Estimate % of Total Estimate % of Total
2010 Total 320,640 100% 69,145 100%
Under 18 Years 82,897 25.9% 16,068 23.2%
18 to 64 Years 198,581 61.9% 42,612 61.6%
65 and Older 39,162 12.2% 10,465 15.1%
Change since 2000 12.6% N/A 10.8% N/A

Source: Portland State University 2010 Population Estimates

As the state capital and county seat, Salem comprised about 42% of Marion County’s population, as well as 34% of Polk County’s population in 2009. The next largest cities in the area are Keizer, Woodburn, and Dallas (see Table 1). Independence, though one of the smallest cities in Polk County, has seen the greatest percentage increase in growth at 35.5% over the past decade, while Keizer has seen the lowest growth at 11.6%. Portland State University estimates the total population of Marion and Polk counties at 320,640 and 69,145 in 2010, respectively.

Table 1. Total Population by Cities
2000 2010 Change (%)
Marion County Keizer 32,515 36,295 11.6%
Salem 137,785 157,460 14.3%
Silverton 7,470 9,655 29.3%
Stayton 6,870 7,815 13.8%
Woodburn 20,310 23,150 14.0%
Polk County Dallas 12,550 23.9%
Independence 6,080 8,240 35.5%
Monmouth 7,780 9,675 24.4%

Source: Portland State University 2010 Population Estimates, PSU 2000 Estimates

As displayed in Figure 2, Marion County has a somewhat younger population than Polk County, Oregon, and the United States, with just over a quarter of residents under the age of 18. Polk County has seen the largest change in median age between 2000 and 2009, rising two years over the period. Oregon’s median age has seen a rise of 1.8 years by comparison, with the median U.S. age rising 1.5 years during that time.


Source: Portland State University 2010 Estimates, U. S. Census 2000 Population Count

Approximately 28.3% of Oregonians aged 25 and up hold a bachelors or higher degree, compared to 20.6% in Marion County and 26.3% in Polk County. Portland State University’s (PSU) population estimates program reports 318,170 residents in Marion County for 2009. With a population of 156,955, Salem is the largest city in Marion County, and serves as both the county seat and state capital. Salem’s city limits extend into Polk County as well. PSU estimates 68,785 as the total population of Polk County in 2009. Dallas, the county seat, had a population of 14,454. Both counties also host several other established, vibrant communities (see Table 1).

As the population continues to rise in Marion and Polk counties, the median resident age remains below the state and national levels (see Figure 2). For 2008, Census estimates show a median age of 34.9 years in Marion County. Residents under age 25 constitute 36 percent of the population, and another 41 percent fall between the ages of 25 and 54. Census numbers show 36 years as the median age in Polk County, with 35 percent of residents under the age 25, and 38 percent of the population between ages 25 and 54. Oregon’s 2008 median age, 37.8 years, is significantly higher than Marion and Polk counties, and sits above the 2008 national median of 36.7 years. Of the population age 25 or older, 82 percent in Marion County possess a high school diploma. Approximately 19 percent have attained a bachelor’s or advanced degree. For Polk County, 91 percent of residents age 25 or older are high school graduates; 27 percent hold a bachelor’s or advanced degree.

Marion and Polk county populations also continue growing in terms of diversity, especially with respect to the Hispanic origin. In Marion County, the share of Hispanic population has grown from 17 percent in 2000 to 23 percent in 2008. Polk County shows smaller but positive gains as well, reporting 9 percent Hispanic population in 2000, and 12 percent in 2008.

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