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ECON orthwest
E CON 0 M I C S . F I NA NeE . P LAN N I N G
Phone. (541) 687-0051
FAX. (541) 344-0562
info@eugene.econw.com
Suite 400
99W.1othAvenue
Eugene, Oregon 97401-3001
Other Offices
Portland. (503) 222-6060
Seattle. (206) 622-2403
29 April 2002
TO:
FROM:
SUBJECT:
Greg Winterowd & Tom Armstrong, Winterbrook Planning Services
Bob Parker and Terry Moore
WOODBURN POPULATION AND EMPLOYMENT PROJECTIONS, 2000-
2020
BACKGROUND
In June 2001, ECONorthwest completed a Goal 9 economic opportunities analysis
(EOA) and economic develop strategy for the City of Woodburn. That project was the
first step the City took to improve the chances that it will get the type and quality of
economic development its citizens desire. It described (1) the City's vision for economic
development, (2) issues related to achieving the economic development vision in
Woodburn, and (3) recommended economic development policies and other changes to
the City's Comprehensive Plan.
The outcome of that project was an economic development strategy that recognizes the
City's locational advantages and encourages economic development and growth in the
City. The strategy states the City does not want to become a bedroom community and
targets specific high-wage industries for future growth.
The EOA and Economic Development Strategy concluded that the City would need
additional land to implement the vision described above. The strategy described a
number of steps the City needed to accomplish to achieve its economic development
vision including seven steps needed for an Urban Growth Boundary amendment. This
memorandum addresses the first two steps:
1. Review the City's coordinated population forecast. Actions the City takes to
support economic development may lead to population and employment growth
beyond that previously forecasted.
2. Review the employment forecast used in the Transportation Systems Plan (TSP).
A revised employment forecast has implications for the TSP and housing.
This memorandum presents population and employment projections for the Woodburn
UGB for the period 2000 through 2020. The projections are predicated on the City's
economic development strategy and assume that land and infrastructure will be
available to support development. Specifically, this memo addresses the following:
1. Existing population and employment forecasts. This memo begins with an
evaluation of the assumptions underlying current projections and comments on
those assumptions given recent population and employment trends.
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 2
2. Revised population and employment projections. This memorandum provides a
range of population and employment based on data from the EOA and the City's
economic development strategy. In summary, we developed new population and
employment forecasts for the Woodburn UGB for the period 2000-2020
3. Allocation of employment to sectors. The employment projection is then
allocated by sector (i.e., industrial, services, government, etc.). Finally, the
sectors are aggregated into four land use categories: commercial, office,
industrial, and public.
4. Implications of population/ employment forecast on land need. The memo
concludes with a brief review of the impact of revised population and
employment on need for land.
In summary, the population and employment forecasts presented in this
memorandum are based on the assumption that the City is successful in
implementing the economic development strategy adopted in 2001.
METHODS
This section describes the methods used for developing the population and
employment projections. Before we describe our methods, it is useful to describe the
limitations of small areas forecasts. The fact that PSU significantly underestimated the
2000 population underscores some of the key problems that emerge with small area
population estimates and forecasts. Following is a discussion of why small area
forecasts are highly uncertain:
. Projections for population in most cities and counties are not based on
deterministic models of growth; they are simple projections of past growth rates
into the future. They have no quantitative connection to the underlying factors
that explain why and how much growth will occur.
. Even if planners had a sophisticated model that links all these important
variables together (which they do not), they would still face the problem of
having to forecast the future of the variables that they are using to forecast
growth (in, say, population or employment). In the final analysis, all forecasting
requires making assumptions about the future.
. Comparisons of past population projections to subsequent population counts
have revealed that even much more sophisticated methods than the ones used
in the study "are often inaccurate even for relatively large populations and for
short periods of time. "1 The smaller the area and the longer the period of time
covered, the worse the results for any statistical method.
. Small areas start from a small base. A new subdivision of 200 homes inside the
Portland Urban Growth Boundary has an effect on total population that is
almost too small to measure. That same subdivision in Woodburn would
lMurdock, Steve H., et. al. 1991. "Evaluating Small-Area Population Projections." Journal of the American
Planning Association, Vol. 57, No.4, page 432.
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 3
increase the community's housing stock by more than 2%-and population by a
similar percentage.
. Especially for small cities in areas that can have high growth potential (e.g.,
because they are near to concentrations of demand in neighboring metropolitan
areas, or because they have high amenity value for recreation or retirement),
there is ample evidence of very high growth rates in short-term; there are also
cases (fewer) of high growth rates sustained over 10 to 30 years.
Because of the uncertainty associated with small area forecasts, this memorandum
presents a range of potential growth rates.
Population
We began the process of forecasting population growth in Woodburn by establishing
the range of likely annual average growth rates for total employment over the twenty-
year period. We estimated the likely range of growth rates by looking at several
indicators:
. Historical population growth in Woodburn and larger areas. We used Census
data to compare population growth in Woodburn, other incorporated cities in
Marion County, all of Marion County, and Oregon over several decades. These
data were used to calculate an annual average growth rate for population for
several different periods. The annual average growth rate for population in
Woodburn was compared to growth rates for population in Marion County, and
the State of Oregon.
. Forecasts of population growth. We used published population forecasts from
the Oregon Office of Economic Analysis to establish the range of expected total
employment growth rates for regions of Oregon. The Oregon Office of Economic
Analysis (OEA) publishes long-term forecasts of population and total nonfarm
employment for Oregon and each individual county. The latest OEA forecast
was published in 1997 and covers the 2000-2040 period.2
The first forecast we did was to apply the City's growth rate implied by its county
coordinated forecast using the 2000 Census as a base. As mentioned above, PSU
significantly underestimated population in 2000. Thus, the 1997 population base
figure of 16,150 used in the coordinated forecast is also low.
We used Woodburn's historical population growth relative to Marion County, and
Oregon and the forecast employment growth rates in these larger areas to establish a
reasonable range of average annual growth rate for total employment in Woodburn
over the 2000-2020 period.
Once a range of average annual growth rates for employment was selected, we applied
those growth rates to 2000 population in Woodburn to estimate 2020 population.
2 The OEA expects to release a draft updated long-term forecast in March 2002. We will incorporate data
from this revised forecast if it is released in time to do so.
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 4
Employment
We began the process of forecasting employment growth in Woodburn by establishing
the range of likely annual average growth rates for total employment over the twenty-
year period. We estimated the likely range of growth rates by looking at several
indicators:
. Historical employment growth in Woodburn and larger areas. We used
confidential ES-202 data provided by the Oregon Employment Department to
identify the level of covered employment in the 97071 (Woodburn) zip code area
in 1990 and 2000. These data were used to calculate an annual average growth
rate for covered employment in Woodburn by sector over the 1990-2000 period.
The annual average growth rate for total employment in Woodburn was
compared to growth rates for total employment in Workforce Region 3 (Marion,
Polk, and Yamhill counties), the Portland PM SA (Clackamas, Columbia,
Multnomah, Washington, and Yamhill counties in Oregon and Clark County,
Washington), and the State of Oregon in the 1990-2000 period. The growth
rates in these larger areas were calculated using published covered employment
data from the Oregon Employment Department.
. Forecasts of employment growth. We used published employment forecasts from
the Oregon Employment Department and the Oregon Office of Economic
Analysis to establish the range of expected total employment growth rates for
regions of Oregon. The Oregon Employment Department publishes 10-year
forecasts of employment growth for Workforce Analysis regions (groups of
counties), the Portland PMSA, and Oregon. The latest Employment Department
forecast was released in July 2001 and covers the 2000-2010 period. The
Oregon Office of Economic Analysis (OEA) publishes long-term forecasts of
population and total nonfarm employment for Oregon and each individual
county. The latest OEA forecast was published in 1997 and covers the 2000-
2040 period.3
We used Woodburn's historical employment growth relative to Workforce Region 3, the
Portland PMSA, and Oregon and the forecast employment growth rates in these larger
areas to establish a reasonable range of average annual growth rates for total
employment in Woodburn over the 2000-2020 period.
Once a range of average annual growth rates for employment was selected, we applied
those growth rates to 2000 total employment in Woodburn to estimate 2020 total
employment. To make this forecast we first adjusted 2000 covered employment in
Woodburn to total employment in Woodburn. The 2000 employment data for the
97071 zip code area is covered employment-that is, it represents employees covered
by unemployment insurance. People working in the area who are not covered by
unemployment insurance are primarily proprietors and officers of corporations. We
used data from the U.S. Bureau of Economic Analysis to convert covered employment
to total employment. Covered employment also does not include seasonal or some
part-time farmworkers, but we do not adjust for this because we expect few
farmworkers to work within Woodburn's UGB, and these workers are unlikely to
create demand for buildable nonresidential land.
3 The OEA expects to release a draft updated long-term forecast in March 2002. We will incorporate data
from this revised forecast if it is released in time to do so.
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 5
With an estimate of 2000 total employment in Woodburn's UGB, we applied the range
of expected growth rates for total employment over the 2000-2020 period to estimate
2020 total employment in the Woodburn UGB area. To estimate 2020 employment by
sector we used assumptions about the distribution of 2020 employment in Woodburn
based on historical growth trends by sector, the outlook for major industries and
employers in Woodburn, and the likely effect of economic development policies and
implementation strategies adopted by the City of Woodburn. The City's policies intend
to attract high-wage manufacturing and distribution industries; the employment
forecasts assume a higher growth rate in the manufacturing sector than would
otherwise be expected. The forecasts also assume corresponding decreases in the
growth rate of other employment sectors. We compared the resulting level of 2020
employment by sector to the 2000 level by sector to make sure the implied growth rate
for each sector was in line with expected trends for that sector.
ORGANIZATION
The remainder of this memorandum is organized as follows:
Population and Employment Trends describes historical population, employment
and socioeconomic trends that are relevant to population projections.
Review of City Population and Employment Forecasts comments on the City's
coordinated population forecast and employment forecast in light of recent trends.
Population and Employment Projections presents our projections of population
and employment in the Woodburn UGB between 2000 and 2020.
Implications of population/ employment forecast on land need discusses the
general impacts the revised population and employment forecasts will have on land
need in Woodburn.
POPULATION AND EMPLOYMENT TRENDS
This section reviews historical population and employment trends in Woodburn. To
provide context, we compare Woodburn with Marion County and Oregon.
POPULATION
Population growth in Oregon tends to follow economic cycles. Oregon's economy is
generally more cyclical than the nation's, growing faster than the national economy
during expansions and contracting more rapidly than the nation during recessions.
This pattern is shown in Table 1, which presents data on population in the U.S.,
Oregon, and selected areas in Oregon over the 1970-2000 period. Table 1 shows
Oregon grew more rapidly than the U.S. in the 1970s and 1990s (which were generally
expansionary periods) but lagged behind the U.S. in the 1980s. Oregon's slow growth
in the 1980s was primarily due to the nationwide recession early in the decade.
Oregon's population growth regained momentum in 1987, growing at annual rates of
1.4%-2.9% between 1988 and 1996. The Willamette Valley received over 70% of the
state's population growth during this period.
Population growth for Oregon and its regions slowed in 1997, to 1.1% statewide, the
slowest rate since 1987. Net migration into Oregon, which is the largest component of
population growth, dropped from 35,000 in 1996 to 18,000 in 1999. The reasons most
often cited for this slowing of population growth are the recovery of the California
economy, the combination of a high cost of living (especially housing) and low wages in
Oregon, and a perceived decline in the quality of Oregon's schools.
The Willamette Valley has always been the center of growth in Oregon. The population
growth rate in the Willamette Valley has exceeded that of the state in every decade
except during the 1970s. Almost 70% of Oregon's population is located in the
Willamette Valley, which contains only 14% of the state's land area. Most of the
Willamette Valley's population is concentrated in the metropolitan areas of Portland,
Salem, and Eugene.4
Woodburn and Marion County have grown faster than other areas in Table 1
throughout the 1970-2000 period. Marion County's share of Oregon's population has
increased from 7.2% in 1970 to 8.4% in 2000. Woodburn's share of Marion County's
population has increased from 5.0% in 1970 to 6.3% in 2000. During the 1990s,
Woodburn grew at a rate of 4.1 % annually-nearly twice than of Marion County, and
more than twice as fast as Oregon.
4 The Willamette Valley is composed of Benton, Clackamas, Lane, Linn, Marion, Multnomah, Polk,
Washington, and Marion counties.
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29 April 2002
Page 7
Table 1. Population in the U.S., Oregon, Willamette Valley, Portland Area, Marion
County, and Woodburn, 1970-2000
Avg. Ann. Growth Rate
Area 1970 1980 1990 2000 70-80 80-90 90-00
U.S. 203,211,926 226,545,805 248,709,873 281,421,906 1.1% 0.9% 1.2%
Oregon 2,091,385 2,633,156 2,842,321 3,421,399 2.3% 0.8% 1.9%
Willamette Valley 1,446,594 1,788,577 1,962,816 2,380,606 2.1% 0.9% 1.9%
North Valley 1,107,546 1,355,645 1,517,866 1,876,425 2.0% 1.1% 2.1%
Marion County 151,309 204,692 228,483 284,834 3.1% 1.1% 2.2%
Woodburn 7,495 11 , 196 13,404 20,100 4.1% 1.8% 4.1%
Sources: U.S. Census and Center for Population Research and Census, Portland State University. Average annual growth rates
calculated by ECONorthwest.
Notes: The Willamette Valley consists of Benton, Clackamas, Lane, Linn, Marion, Multnomah, Polk, Washington, and Marion
Counties. The North Valley consists of Clackamas, Marion, Multnomah, Polk, Washington, and Marion Counties.
Between 1990 and 1999, almost 70% of Oregon's total population growth was from net
migration (in-migration minus out-migration), with the remaining 30% from natural
increase (births minus deaths). Migrants to Oregon tend to have the same
characteristics as existing residents, with some differences-recent in-migrants to
Oregon are, on average, younger and more educated, and are more likely to hold
professional or managerial jobs, compared to Oregon's existing population. The race
and ethnicity ofin-migrants generally mirrors Oregon's established pattern, with one
exception: Hispanics make up more than 7% of in-migrants but only 3% of the state's
population. The number-one reason cited by in-migrants for coming to Oregon was
family or friends, followed by quality oflife and employment.5
Of note is the difference between the 2000 Census count for Woodburn and the
Portland State University Center for Population Research and Census 2000 population
estimate. The Census indicated that the 2000 population was 20,100, while PSU
estimated the 2000 population was 17 ,840-a difference of 2,260 persons. Applying
the Census data yields a 4.1% average annual growth rate between 1990 and 2000;
using the PSU estimate yields a 2.9% growth rate. For 2000, the Census, which is a
count, is more reliable than PSU, which is an estimate based on additions to the
previous Census count (1990).
EMPLOYMENT
Table 2 shows employment growth in the 97071 zip code area (which includes
Woodburn and the surrounding area) over the 1990-2000 period. The sectors used in
Table 2 are those defined by ODOT for use in transportation planning. Table 2 shows
that total employment in the Woodburn area has grown at an average annual rate of
4.4% in the 1990s.
Employment growth in the Woodburn area was led by the Retail sector, which added
1,504 jobs or 51% of total growth in the 1990-2000 period. The Retail sector also led
the Woodburn area in the rate of employment growth, with an 8.6% annual average
that is over twice the annual average for total employment growth. The Other and
Service sectors combined contributed 32% of total employment growth in the
Woodburn area and grew at about the same rate as total employment. The Education
5 State of Oregon, Employment Department. 1999. 1999 Oregon In-migration Study.
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29 April 2002
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sector contributed 10% of employment growth in the Woodburn area but had the
second-fastest average annual employment growth rate, 6.1%.
Table 2. Covered employment growth by sector in the 97071 zip code area, 1990-
2000
Sector
Agriculture
Industrial
Retail
Service
Education
Government
Other
Total
SICs
00-09
10-14,22,24-39
52-59
48-49,60-67, 70-81, 83-89
82
91-94
15-17,19-20,23,40-47,50-51,95-99
1990
949
1,006
1,166
788
352
142
1 ,149
5,552
2000
1,122
960
2,670
1,207
638
225
1 ,696
8,518
Growth
173
-46
1,504
419
286
83
547
2,966
AAGR
1.7%
-0.5%
8.6%
4.4%
6.1%
4.7%
4.0%
4.4%
Source: ECONorthwest, from confidential ES-202 data provided by the Oregon Employment Department.
Note: Employment in the 97071 zip code area identified by sorting Marion County data by addresses of record. Employers in
Woodburn with addresses outside of the 97071 zip code area may not appear in this summary.
Table 3 shows covered employment growth in the Woodburn area, Workforce Region 3
(Marion, Polk, and Yamhill counties), the Portland PMSA, and Oregon over the 1990-
2000 period. Table 3 shows that covered employment in the Woodburn area grew at a
faster annual average rate than in other areas shown in Table 3. The annual average
rate of covered employment in Woodburn was 1.4% to 1.8% faster than in Workforce
Region 3, the Portland PMSA, or Oregon (in other words, Woodburn employment grew
at a rate roughly 50% greater than employment in those jurisdictions).
Table 3. Covered employment growth in Woodburn,
Workforce Region 3, the Portland PMSA, and Oregon,
1990-2000
Area 1990 2000 AAGR
Woodburn 5,552 8,518 4.4%
Workforce Region 3 132,889 172,173 2.6%
Portland PMSA 715,454 962,833 3.0%
Oregon 1,236,243 1,607,911 2.7%
Source: ECONorthwest, from Oregon Covered Employment and Payrolls by Industry
and County and Employment and Payrolls in Washington State by County and Industry.
Note: Workforce Region 3 consists of Marion, Polk, and Yam hill counties. The Portland
PMSA consists of Clackamas, Columbia, Multnomah, Washington, and Yamhill counties
in Oregon and Clark County, Washington.
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29 April 2002
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REVIEW OF CITY POPULATION AND EMPLOYMENT FORECASTS
Population (expressed as households) and employment forecasts are the key inputs in
determining land need. Any forecast is, by definition, uncertain. That uncertainty
increases as the geographic region for the forecast decreases and as the duration of
the forecast increases.
ORS 195.036 requires counties to "establish and maintain a population forecast for
the entire area within its boundary for use in maintaining and updating
comprehensive plans" and to "coordinate the forecast with local governments within
its boundaries." The County facilitated a series of meetings during 1997 and 1998,
informally called the "Growth Management Forum" where county, city and council of
governments staff discussed appropriate projects for the cities in Marion County.
Marion County completed this process in October 1998.6
There is no statutory requirement for coordinated employment forecasts. Many cities,
however, develop employment forecasts for transportation planning purposes. This is
the case with Woodburn, which developed an employment forecast during the
development of its Transportation System Plan (TSP). Woodburn's TSP was adopted in
1996, and revised again in 2001.
Population
The coordinated 2020 population forecast for Woodburn is 26,290. Table 4 shows the
coordinated population forecasts for Marion County and incorporated cities within
Marion County. The County adopted the forecasts in 1998; the forecasts use a 1997
base year and extend to 2020, a 23-year period.
The Office of Economic Analysis forecast 2020 population in Marion County to be
350,952. This figure serves as the control total for the coordinated population
forecasts-all of the population forecast for incorporated cities and rural areas needs
to sum to this total. Given the control total, and the process used to coordinate the
forecasts, the city-level forecasts are more of an allocation than a forecast.
6 Marion County Ordinance Number 1091, October 21,1998.
Parker and Moore to Winterowd and Armstrong 29 April 2002 Page 10
Table 4. Marion County coordinated population forecasts,
Marion County and incorporated cities, 1997-2020
1997 (PSU 2000 AAGR 97-
City Est.) (Census) 2020 2020
Aumsville 2,820 3,003 5,010 2.5%
Aurora 675 655 930 1.4%
Detroit 380 262 535 1.5%
Donald 630 608 1,050 2.2%
Gates 489 471 800 2.2%
Gervais 1,220 2,009 2,168 2.5%
Hubbard 2,205 2,483 3,105 1.5%
Idanha 200 232 230 0.6%
Jefferson 2,300 2,487 2,895 1.0%
Mill City 310 1,537 420 1.3%
Mt Angel 3,020 3,121 4,365 1.6%
St Paul 350 354 475 1.3%
Salem/Keizer 152,530 169,127 255,338 2.3%
Scotts Mills 315 312 420 1.3%
Silverton 6,675 7,414 9,965 1.8%
Stayton 6,290 6,816 9,250 1.7%
Sublimity 2,145 2,148 3,590 2.3%
City Totals 200,034 224,338 329,199 2.2%
Unincorporated 67,666 60,496 21,753 -4.8%
Marion Countv 267.700 284.834 350.952 1.2%
Source: Marion County
The forecast uses a 1997 base population of 16,150 persons. Given Woodburn's
assumed year 2000 population of 17,840 the coordinated forecast translates into an
average annual growth rate of 2.0% over the 2000-2020 period. This rate exceeds the
forecast annual average population growth rate in Marion County (1.4%), the North
Valley region (1.3%) and Oregon (1.2%), but is less than the 4.1% annual average
growth rate experienced in Woodburn in the 1990-2000 period.
A letter data December 8, 1997 from Rob Hallyburton to Mayor Nancy Kirksey
describes the process the County used to develop the preliminary coordinated
population forecasts for Marion County and its incorporated cities. An attachment to
that letter describes the method used to develop the city population projections. The
County used a method developed by the Oregon Office of Economic analysis. That
process projected to a 2015 county control total of 354,561, is as follows:
1. The historical growth rates for each city, in five-year increments back to 1960-
65, were calculated.
2. Weights were assigned to the average annual growth rates giving the most
recent growth rates the most emphasis. The weights were based on a
calculation "last year of the five-year period minus 1960." Therefore the 1960-
65 period was weighted 5 (1965 minus) 1960 and 1990-95 was weighted 35
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 11
(1995 minus 1960). A weighted average annual growth rate for each city for the
period 1960 to 1995 was then calculated.
3. The weighted city growth rate projections were finished by assuming the gap
between the city weighted average growth rate and the county weighted average
growth rate would be half closed by the end of the projection period. For
example, the weighted average growth rate for the county is 3.18%, and the
weighted average rate for Aumsville is 5.10%. The difference, 1.92, is halved
(0.96) and added back to the lower figure (the county's 3.18% in this case), for a
projected average growth rate of 4.14%.
4. The weighted average annual growth rate for each city was then applied,
assuming linear growth. The sum of the city projections did not, however, agree
with the OEA county totals for each year of the projection. An adjustment factor
was then calculated by dividing the smaller of the two by the larger (in each
case the OEA projection was smaller).
5. The final step of the project employed by OEA included discussing the results
with the affected jurisdictions, and making adjustments, as they found
appropriate.
The description should make it clear that the forecast method is logical but,
ultimately, arbitrary?: different year and different weights could have been used; there
is not explicit consideration of factors that might cause growth rates to be different in
the future. The method resulted in a 2015 population forecast of 30,319 persons for
Woodburn after step three of the process described above. This equates to a 3.42%
average annual growth rate. Applying the adjustment factor described in step four
resulted in a 2015 population forecast of 23,769 persons, or a 1.3% average annual
growth rate. The weighted average annual growth rate for Marion County (step 2) was
3.18%, but the OEA rate was a much lower rate of about 1.6%.8
It is important to note that step 4 of this method uses a somewhat arbitrary approach
to adjusting local growth rates to get the city forecasts to sum to the county control
total. In short, the adjusted average annual growth rate of 1.73% is inconsistent with
historical population trends and results in figures that are likely to be systematically
low. The County's numbers show the 2000 forecast for Woodburn was 17,653, a figure
that fell far below the 2000 Census count of 20, 100. Even the unadjusted forecast
underestimated the 2000 population, resulting in a 2000 forecast of 18,309 persons.
The letter of December 8, 1997, also includes a set of population projections for the
period 1998-2020 based on three different growth rates and two base populations
(16,150 and 18,744). Table 5 summarizes those projections.
With the exception of the Marion County proposal of 2.2% annual growth for
Woodburn, all of the projections result in 2020 populations that are higher than the
7 By "arbitrary" we do not mean wrong, unsupportable, or capricious; we mean that many assumptions
were made where other assumptions could be justified equally well.
8 There are some discrepancies in the figures presented in the memo and the final forecasts that we
cannot explain. The adopted average annual growth rate for Marion County is 1.53%; the preliminary
forecasts result in a slightly higher growth rate.
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29 April 2002
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adopted population forecast of 26,290 persons. The December 8 materials give no
justification for why Marion County staff proposed a 2.2% average annual growth rate
for Woodburn when the evidence clearly indicates the City has grown at much higher
rates both in the short term (1990-95) and long term (1960-95).
Part of the rationale probably lies in the OEA control rate of 1.53%. Because the
County is forecast to growth at a slower rate, having city rates-particularly in larger
cities-that greatly exceed that rate will require other cities to adopt lower rates.
Table 5. Woodburn population projections, 1998-2020,
Projections developed by Marion County staff
Scenario 1998 2000 2005 2010 2015 2020
Base population of 16,150
Growth rate of 2.2% (Marion County Proposal)
Base population 16,150 16,868 18,897 20,969
Growth 718 2,029 2,072
Growth rate of2.92% (AveraQe for Period 1990-1995)
Base population 16,150 17,107 19,755 22,812
Growth 957 2,648 3,057
Growth rate of 3.4% (Historical Average for Period 1960-1995
Base population 16,150 17,267 20,409 24,122
Growth 1,117 3,142 3,713
Base Population of 18,774
Growth rate of 2.2% (Marion County Proposal)
Base population 18,774 19,609 21,863 24,376
Growth 835 2,254 2,513
Growth rate of2.92% (AveraQe for Period 1990-1995)
Base population 18,774 19,886 22,964 26,519
Growth 1,112 3,078 3,555
Growth rate of 3.4% (Historical Average for Period 1960-1995
Base population 18,774 20,072 23,725 28,042
Growth 1.298 3.653 4.317
Source: Marion County
23,380 26,067
2,411 2,687
26,343 30,421
3,531 4,078
28,512 33,700
4,390 5,188
27,718 30,302
3,342 2,584
30,623 35,363
4,104 4,740
33,144 39,175
5.102 6.031
In summary, the methods used by County to develop the coordinated population
forecast for Woodburn do not recognize historical growth patterns or the City's
economic development vision. They arrive at an average annual growth rate of about
2.2% without explaining the rationale for choosing that rate. Implicitly one of the
reasons was to get all of the City forecasts to sum to the County control total. The
2020 forecast for Woodburn would be more accurately called an allocation based on a
political process that has little to do with sound forecasting techniques.
Employment
To our knowledge a coordinated forecast of employment in Woodburn has not been
developed. To estimate future travel demand, the Woodburn Transportation System
Plan (June 1996) estimated employment growth of 3,221 over the 1991-2020 period.
With a 1991 employment level of 5,045 this translates into a 2020 employment level of
8,266 or an average annual growth rate of 1.7%. This rate exceeds the forecast annual
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 13
average employment growth rate in Marion County (1.2%), the North Valley region
(1.0%) and Oregon (1.0%).
If the historical trends implied by the data in Tables 2 and 3 were used for forecasting,
the forecast of employment growth in Woodburn would be higher.
REVISED POPULATION AND EMPLOYMENT PROJECTIONS
This section presents revised population employment projections for the Woodburn
Urban Growth Boundary for the period from 2000 to 2020. The projections are based
on the methods described earlier in this memorandum and result in a range of
possible growth rates.
Population
Figure 1 shows that Woodburn has historically grown at rates faster than larger
geographic areas. Despite the recession Oregon experienced during the 1980s,
Woodburn continued to grow at rates more than twice that of the state. This suggests
that Woodburn's location and other factors have provided the City with a comparative
growth advantage.
Figure 1. Historical population growth rates, by decade 1970-2000
AAGR
4.5%
4.0%
3.5%
3.0%
2.5%
2.0%
1.5%
1.0%
0.5%
0.0%
70-80
80-90
90-00
IIiIiI US IiIiI Oregon [] Marion County [] Woodburn I
One common approach to projecting population is the ratio method. This method
assumes that the ratio between the population of a smaller and larger geographic area
will remain constant over time, and then forecasts the population of the smaller are as
a percentage of a forecast for a larger area. Table 6 shows historical and forecast
population for Marion County and Woodburn and the percent of County population
accounted for by Woodburn. The results show a trend where Woodburn accounts for
increasing share of about 0.5% of the County's population each decade. In summary,
Woodburn's share of Marion County population increased from 5.0% in 1970 to 7.1%
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 14
in 2000. The 2020 Coordinated forecast ignores this trend and actually assumes that
Woodburn will account for a slightly smaller share of Marion County's population.
Historical
Table 6. Ratio of Woodburn to County population, 1970-2000 and 2020
Area
Marion County
Woodburn
% of Count Po
1970
151,309
7,495
5.0%
1980
204,692
11 ,1 96
5.5%
1990
228,483
13,404
5.9%
2000
284,834
20,100
7.1%
Forecast
2020
378,208
26,290
7.0%
Source: us. Census, Marion County Coordinated Population forecast; analysis by ECONorthwest
Table 7 shows population projections for the Woodburn UGB using several different
methods. The methods result in average annual growth rates from 1.43% to 4.13%. Of
note is the second method that applies Woodburn's current coordinated growth rate of
2.1 % to the 2000 population base of 20, 100. This increases the 2020 forecast from
26,290 to 30,459 persons-an increase of over 4,000 persons.
Table 7. Woodburn population projections using different methods, 2000-2020
Method
Adopted
Adopted (2000 base pop)
2000 Ratio (2000 base pop)
2000 Increasing ratio (2000 base pop)
1990-2000 AAGR
1970-2000 AAGR
2000
17,210
20,100
20,100
20,100
20,100
20,100
2005
19,133
22,301
21,576
22,391
24,614
23,692
2010
21,271
24,743
23,161
24,943
30,141
27,926
2015
23,152
27,453
24,863
27,786
36,910
32,916
2020
26,290
30,459
26,689
30,952
45,198
38,798
AAGR
2.10%
2.10%
1.43%
2.18%
4.13%
3.34%
Source: Marion County Coordinated Population forecast; ECONorthwest
The "Adopted" projection is obviously flawed: not because it is conceptually flawed, but
because its starting population has been shown by the 2000 Census to be incorrect.
All the other forecasts are more or less reasonable in concept. They probably bound
the range of future growth, but the boundaries are wide (from 6,000 to 25,000 new
people). Narrowing the range requires more thinking, assumptions, and decisions. One
must understand that the numbers in Table 7 are really just arithmetic
manipulations: assumptions about growth rates. The real issue is: what factors would
cause a future growth rate to be approximately equal to, higher, or lower than rates
observed in the past?
From that perspective, most of the evidence we evaluated about growth and the
economy n Woodburn (see the City's Economic Opportunity Analysis, 2001) suggests
that it will continue to grow faster than the average for Marion County. We think a
reasonable range of annual population growth rate assumptions for Woodburn is 2.2%
to 3.2%. Figure 2 shows the results of applying a 2.3% (low), 2.8% (medium), and
3.3% (high) average annual growth rate to the 2000 base population of 20, 100. All of
the scenarios use a compounding method.
The low growth scenario results in a 2020 population projection of 31,64, compared to
the coordinated forecast of 26,290. The high rate assumption results in a 2020
population of 38,477, while the medium rate assumption results in a 2020 population
of 34,674.
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29 April 2002
Page 15
Figure 2. Revised Woodburn UGB population forecast, 2000-2020, low (2.3%
AAGR), medium (2.8%) AAGR, and high (3.3% AAGR) assumptions
Population
40,000
35,000
30,000
25,000
20,000
2000
2005
2010
2015
2020
I-+- High - Medium ---.- Low I
That wide range of forecasts is often disappointing to planners, elected officials, and
citizens: should we be able to do a better job? The answer is "no," and the description
of the problems with forecasting for small areas on page 2 of this memorandum
explains why. The future is uncertainty; a range of forecasts reflects that uncertainty;
a single point-estimate does not.
Employment
Table 3 does not show an employment forecast for Woodburn because the State of
Oregon does not produce employment forecasts for areas smaller than counties or
regions (groups of counties). Table 3 shows that the annual average rate of covered
employment growth in Woodburn was 1.4% to 1.8% faster than in Workforce Region 3,
the Portland PMSA, or Oregon over the 1990-2000 period. If this pattern persists, then
the forecasts shown in Table 3 suggest that employment in Woodburn will grow at an
average annual rate of 2.6% to 2.9% in the 2000-2010 period or 2.3% to 3.0% in the
2000 to 2020 period.
We expect the pattern of faster employment growth in Woodburn than in Workforce
Region 3, the Portland PMSA, and Oregon to continue over the 20-year forecast period
for several reasons:
. Woodburn is at the periphery of the Portland-Vancouver and Salem
metropolitan areas, and it is typical for small towns at the periphery of urban
areas to grow faster than the urban area as a whole.
. Reluctance and inability to expand Portland's Urban Growth Boundary will limit
the supply of greenfield commercial and industrial development sites in the
Portland area. Woodburn is well-poised to attract a share of commercial and
industrial development that might otherwise occur in the Portland area because
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 16
of its location near Portland, access to 1-5, and supportive policies that will
create development sites and encourage development.
In this context, given historical growth rates and forecast growth for Workforce Region
3 and the Portland PMSA, we expect employment Woodburn to grow at an average
annual rate of 2.3% to 3.0% over the 20-year planning period. That range is similar to
the one we recommend for population. The implication is that Woodburn will be
adding jobs at about the same rate that it will be adding population, which is
consistent with Woodburn's goals (it does not want to become a bedroom community,
which would mean population would be growing at a significantly greater rate than
employment). Since we can imagine combinations of economic factors and public
policy (both state and local) that could cause the population growth rate to be either
higher (bedroom community) or lower (siting of large industrial or commercial
employers) than the employment growth rate, assuming them to be equal for the
purposes of long-run planning seems reasonable.
To apply this range of growth rates to Woodburn's employment in 2000, we must
adjust data in Table 8 to reflect total rather than covered employment. Table 8
includes only covered employment, which consists of employees covered by
unemployment insurance laws. Covered employment omits several categories of
workers, most notably sole proprietors and corporate officers who are not covered by
unemployment insurance laws. Analysis of employment data from the U.S. Bureau of
Economic Analysis, which reports both wage and salary employment (covered) and
total employment, shows that nonfarm wage and salary employment was 82% of
nonfarm total employment in 1998. We do not make any adjustments for farm
employment on the assumption that there will be little growth in farm employment
inside Woodburn' UGB.
Table 8 uses this 82% ratio to convert Woodburn's covered employment in 2000
(8,518) to total employment in 2000 (10,388). With this baseline total employment,
Table 8 uses average annual employment growth rates at the low (2.3%), medium
(2.65%), and high (3.0%) end of the range of expected employment growth rates to
forecast Woodburn's total employment in 2020. This results in a forecast of total 2020
employment in the Woodburn UGB of 16,370 (low), 17,527 (medium), or 18.762 (high).
Table 8. Forecast total employment
in Woodburn's UGB, 2000-2020
Baseline Employment 2000
Covered Employment
Covered/Total Employment
Total Employment
Forecast Employment 2020
Low-2.3%
Medium-2.65%
High-3.0%
Employment Growth 2000-2020
Low
Medium
High
8,518
0.82
10,388
16,370
17,527
18,762
5,982
7,139
8,374
Source: ECONorthwest.
To allocate expected total employment growth in Woodburn to employment sectors,
the trend in shares by sector over the 1990-2000 period and expected future trends in
Parker and Moore to Winterowd and Armstrong
29 April 2002
Page 17
employment by sector were used to make assumptions about the distribution of
employment by sector in 2020. The result of applying these assumptions to expected
employment growth in Woodburn is shown in Table 9.
Table 9. Employment by sector in Woodburn's UGB, 2000-2020
Sector
Agriculture
Industrial
Retail
Service
Education
Government
Other
Total
Employment Share
1990 2000 2020
17% 13% 5%
18% 11 % 16%
21% 31% 34%
14% 14% 16%
6% 7% 8%
3% 3% 3%
21% 20% 18%
100% 100% 100%
Low
819
2,619
5,566
2,619
1,310
490
2,947
16,370
2020 Employment
Medium
876
2,804
5,959
2,804
1 ,402
527
3,155
17,527
High
938
3,002
6,379
3,002
1,501
563
3,377
18,762
Source: 1990 and 2000 employment shares by ECONorthwest from confidential ES-202 data provided by the Oregon
Employment Department. Year 2020 employment distribution provided by ECONorthwest.
Table 10 takes the forecast 2020 employment by sector in Table 9 and uses 2000
employment by sector to calculate employment growth by sector in Woodburn in the
2000-2020 period. To make this calculation, covered 2000 employment by sector from
Table 3 must be converted to total 2000 employment by sector using the 82% ratio
applied in Table 9.
Table 10. Employment growth by sector in Woodburn's UGB, 2000-2020
Covered Total Employment Growth 2000-2020
Sector 2000 2000 Low Medium High
Agriculture 1,122 1,368 -549 -492 -430
Industrial 960 1,171 1 ,448 1,633 1,831
Retail 2,670 3,256 2,310 2,703 3,123
Service 1,207 1,472 1,147 1,332 1,530
Education 638 778 532 624 723
Government 225 275 215 252 288
Other 1 ,696 2,068 879 1 ,087 1 ,309
Total 8,518 10,388 5,982 7,139 8,374
Source: ECONorthwest.
Employment growth by sector in Table 10 was allocated to four categories for use in
projecting the demand for non-residential land in Woodburn: Commercial, Office,
Industrial, and Public. The sectors included in each land use category are:
. Commercial: Retail
. Office: Service
. Industrial: Agriculture, Industrial, and Other
. Public: Education and Government
The results of this allocation are shown in Table 11.
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29 April 2002
Page 18
Table 11. Employment growth in Woodburn's
UGB by land use category, 2000-2020
Land Use
Category
Commercial
Office
Industrial
Public
Total
Employment Growth 2000-2020
Low
2,310
1,147
1,778
747
5,982
Medium
2,703
1,332
2,228
876
7,139
High
3,123
1,530
2,710
1 ,011
8,374
Source: ECONorthwest.
Parker and Moore to Winterowd and Armstrong 29 April 2002 Page 19
APPENDIX: HISTORICAL POPULATION DATA
Table A-1. Historic population trends, Marion County and Marion County cities,
1900-2000
City 1900 1920 1930 1940 1950 1960 1970 1980 1990 2000
Aumsville 171 153 174 281 300 590 1,432 1,650 3,003
Aurora 122 229 215 228 242 274 306 523 567 655
Detroit 206 328 367 331 262
Donald 126 114 164 187 201 231 267 316 608
Gates 189 250 455 499 471
Gervais 224 268 254 332 457 438 746 799 992 2,009
Hubbard 213 320 330 387 493 526 975 1,640 1,881 2,483
Idanha 442 295 280 319 289 232
Jefferson 273 417 391 479 636 716 936 1,702 1,805 2,487
Keizer 21,884 32,203
Mill City 1,289 1,451 1,565 1,555 1,537
Mt Angel 537 936 823 1,032 1,315 1,428 1,973 2,876 2,778 3,121
St Paul 160 148 183 226 254 346 312 322 354
Salem 4,258 17,679 26,266 30,908 40,087 45,245 62,960 89,233 107,793 136,924
Scotts Mills 208 153 227 217 155 208 249 283 312
Silverton 656 2,251 2,462 2,925 3,146 3,081 4,301 5,168 5,635 7,414
Stayton 324 649 797 1,085 1,507 2,108 3,170 4,396 5,011 6,816
Sublimity 172 214 280 367 490 634 1,077 1,491 2,148
Turner 289 283 414 610 770 846 1,116 1,218 1,199
Woodburn 939 1,656 1,675 1,982 2,395 3,120 7,495 11,196 13,404 20,100
Marion County 27,713 47,187 60,541 75,246 101,401 120,888 151,309 171,700 230,028 284,834
OreQon 413,536 783,389 953,786 1 ,089,684 1,521,341 1 ,768,687 2,091 ,533 2,633,105 2,842,321 3,421 ,399
Percent Change
Aumsville -11% 14% 61% 7% 97% 143% 15% 82%
Aurora 88% -6% 6% 6% 13% 12% 71% 8% 16%
Detroit 59% 12% -10% -21%
Donald -10% 44% 14% 7% 15% 16% 18% 92%
Gates 32% 82% 10% -6%
Gervais 20% -5% 31% 38% -4% 70% 7% 24% 103%
Hubbard 50% 3% 17% 27% 7% 85% 68% 15% 32%
Idanha -33% -5% 14% -9% -20%
Jefferson 53% -6% 23% 33% 13% 31% 82% 6% 38%
Keizer 47%
Mill City 13% 8% -1% -1%
Mt Angel 74% -12% 25% 27% 9% 38% 46% -3% 12%
St Paul -8% 24% 23% 12% 36% -10% 3% 10%
Salem 315% 49% 18% 30% 13% 39% 42% 21% 27%
Scotts Mills -26% 48% -4% -29% 34% 20% 14% 10%
Silverton 243% 9% 19% 8% -2% 40% 20% 9% 32%
Stayton 100% 23% 36% 39% 40% 50% 39% 14% 36%
Sublimity 24% 31% 31% 34% 29% 70% 38% 44%
Turner -2% 46% 47% 26% 10% 32% 9% -2%
Woodburn 76% 1% 18% 21% 30% 140% 49% 20% 50%
Marion County 70% 28% 24% 35% 19% 25% 13% 34% 24%
OreQon 89% 22% 14% 40% 16% 18% 26% 8% 20%