County Growth Management Population Projections …

State of Washington Office of Financial Management

2017 ProjectionS

County Growth Management Population Projections by Age and Sex: 2010?40

Forecasting & Research Division

August 2018

To accommodate persons with disabilities, this document is available in alternative formats by calling the Office of Financial Management at 360-902-0555. TTY/TDD users should contact OFM via the Washington Relay Service at 711 or 1-800-833-6388.

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Table of Contents

1 Overview

2 Growth Management Act population projections: 2010?40

2 Section 1: Comparison of 2011 and 2017 state forecasts

2 Figure 1: State population forecast comparison, total population

3 Table 1: Comparison of 2017 and 2011 state forecasts

3 Table 2: Comparison of projected natural increase from 2017 and 2011 state forecasts

4 Table 3: Comparison of projected net migration from 2017 and 2011 state forecasts

4 Methodology and assumptions

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Figure 2: Comparison of averaged migration projections from econometric/cohort component method II and other methods from 2017 state forecasts

7 Table 4: Components of population change from the 2017 state forecast, 2000?40

8 Section 2. County population projections: 2010?40

8 General discussion

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Table 5: Comparison of 2012 GMA medium series projected population to 2017 OFM estimates for the year 2017

10 Discussion of county projection methods and assumptions

13 Discussion of high- and low-projection alternatives

14 Section 3. State and county growth profiles

95 Section 4. Final projections of the total resident population for the Growth Management Act: 2010?40

96 High series 97 Medium series 98 Low series

99 Section 5. Projections of the total resident population for the Growth Management Act: 2010?40 by single year after 2015

100 High series 102 Medium series 104 Low series

106 Appendix A. Data concepts

107 Appendix B. Historical data 108 Historical and projected population for growth management and other purposes 109 Historical and projected net migration for growth management and other purposes

Table of Contents (continued)

111 Appendix C. Population age 65 and over 111 Population by age 65 and over 112 Population age 65 and over as a percentage of total county population 113 Appendix D. 2017 GMA total fertility rate by county and change from 2012 114 Appendix E. RCW 43.62.035 Determining Population ? Projections

Overview

Pursuant to RCW 43.62.035, this document contains county population projections prepared by the Office of Financial Management for planning under the Growth Management Act. State and county populations are provided at five-year intervals between 2010 and 2040. The additional single-year interval projections between 2015 and 2040 are developed to accommodate the various GMA planning targets specified by counties. The GMA projections present high-, medium- and low-growth expectations for each county. Any projections are statements about the future based on a particular set of assumptions. The GMA medium series is considered the most likely because it represents a future based on assumptions that have been validated with past and current information. However, assumptions may not hold true if factors influencing population growth change. The high and low series reflect general uncertainty bands for growth over the next 30 years. These assumptions are based on the historical high and low migration patterns for each county and current factors affecting the economic base and attractiveness of specific areas in the state. The alternative series represent the fundamental unpredictability of long-range projections. They should be considered for planning purposes if the social and economic environment impact on demographic trends predicted in the middle series does not hold. As indicated in RCW 36.70A.110 and RCW 36.70A.115, local officials are responsible for selecting a 20-year GMA planning target that is within the high- and low-growth projections prepared by OFM. If the county shows population dynamics that would invalidate the GMA projections before the next GMA projection update, the county may petition OFM to make changes to its projection. Caution is recommended when users see variation between current population estimates and longterm projections. Users should consider allowing long-term projections time to play out before changing them. Often, migration or fertility may seem to change dramatically for a year or two, but such changes usually return to a longer-term trend within a few years. However, if significant structural changes occur with a strong demographic impact -- such as a recession -- adjustments to the projections should be considered within the high and low framework.

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Growth Management Act Population Projections: 2010?40

Section 1: Comparison of 2011 and 2017 state forecasts

The 2017 Growth Management Act county projections are developed using the November 2017 Washington state population forecast as the control. The top-down approach is used because at the state level, more data is available, the population dynamics are more stable and projections have been demonstrated to be more accurate. For the medium series, total population and the components of change for each county over the projection period are reconciled with the total state population projection for each single-year interval.

The state population forecast uses a cohort component model. As shown in Figure 1, the 2017 state forecast projects higher population growth between 2015 and 2040 than in 2011 (the base for the 2012 GMA state totals). Both the 2011 and 2017 state forecasts are based on the 2010 census counts of the population by single year, age and gender. The difference is that the 2017 forecast includes the Office of Financial Financial Management's annual state population estimates and the most recent fertility rates, mortality rates and net migration trends. Each year, when the state population estimate replaces forecasted data, growth trends are re-evaluated and adjusted before the age-specific population is projected. This is a standard demographic forecast procedure. Estimates are regarded as more accurate because they are developed with actual data on births and deaths, with migration determined by separate models based on current data. The forecast, on the other hand, is solely based on assumptions of future growth trends for fertility, mortality and migration.

Figure 1. State population forecast comparison, total population

10,000,000 9,000,000 8,000,000 7,000,000 6,000,000 5,000,000 4,000,000 3,000,000 2,000,000

2017 Forecast 2011 Forecast Actual

1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030 2032 2034 2036 2038 2040

When OFM produced the 2011 state forecast, the state economy was still at the bottom of the Great Recession. Lacking definitive information, the 2011 forecast made no attempt to predict when the economic rebound would happen. Instead, it adopted the 30-year average growth for the future. Since then, the technology industry around the greater Seattle area fueled explosive growth, accelerating the economic recovery. The dramatic increase in jobs attracted more migrants to Washington than expected. Subsequently, migration assumptions in the 2017 GMA projections have been adjusted in response to the impacts of economic recovery on population growth.

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Table 1 compares the total population from the two forecasts. For the entire forecast period, the 2017 forecast has projected 451,000, or more than 5 percent, more population growth. The largest difference occurred during the 2015?20 period. The 226,500 more projected persons (including additional growth from 2010?15) account for about 50 percent of the total difference over the entire forecast period. This rapid growth is related to the economic boom that was not anticipated in the 2011 state forecast. The expectation in the 2017 forecast is that the peak of the economic boom will have passed by 2020. Moving forward, population growth is expected to gradually return to a point that is close to the three-decade average by the end of the forecasting horizon.

Table 1: Comparison of 2017 and 2011 state forecasts

Period 2010 2010-15 2015-20 2020-25 2025-30 2030-35 2035-40

2017 Forecast 6,724,540 7,061,410 7,638,415 8,085,043 8,503,178 8,894,306 9,242,022

2011 Forecast

7,022,200 7,411,977 7,793,173 8,154,193 8,483,628 8,790,981

Difference Between the 2

Forecasts

39,210 226,438 291,870 348,985 410,678 451,041

Percentage Difference Between

the 2 Forecasts

0.56 3.06 3.75 4.28 4.84 5.13

To better understand the change of growth trends, we also compare the demographic components between the two forecasts. For illustration purposes, Table 2 shows only the comparison of the natural increase, defined as births minus deaths. For the 2010?15 period, the 2011 forecast overprojects the natural increase by almost 5 percent. This is due to two reasons: Women delayed childbearing during the recession, which resulted in a decline of the total number of births. And people are expected to live longer than assumed. After 2015, the 2017 forecast projects more births, even though the total fertility rate is expected to continue to decline. This is because the increase in migration adds more childbearing-age women to the population.

Table 2: Comparison of projected natural increase from 2017 and 2011 state forecasts

Period 2010-15 2015-20 2020-25 2025-30 2030-35 2035-40

2017 Forecast 183,587 182,920 180,251 155,935 124,128 99,716

2011 Forecast 192,751 179,777 164,196 136,020 104,435 82,353

Difference Between the 2

Forecasts (9,164)

3,143

16,055

19,915

19,693

17,363

Percentage Difference Between

the 2 Forecasts (4.75)

1.75

9.78

14.64

18.86

21.08

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Migration is the most variable and difficult demographic component to measure and predict. The crash of financial and housing markets led to the Great Recession, which began in the last quarter of 2007. Washington then observed a four-year continuous decline in migration, caused by the highest unemployment rates since 1983, and a severe housing market correction. The state total net migration level reached its lowest point at 4,800 in 2011. (For details, see the 2011 state forecast official report at .) Such a low level of migration and the lingering recession had a significant influence on the short-term migration assumptions in the 2011 state forecast. Without information on how and when the state economy would recover, the long-term migration assumptions were developed based on a 30-year annual average of 45,000.

Table 3 compares the migration from the two forecasts. The major correction happens during the 2015?20 period. The 2017 GMA estimated and projected net migration for this period is 394,100. This is about 184,100, or almost 88 percent, more migrants than expected in the 2011 forecast. These adjustments were made based on the unique economic and demographic changes that occurred after the release of the 2011 state forecast and the anticipated impacts on domestic and international migration.

The long-term migration expectation received only a modest adjustment for three possible reasons. First, the recent gains in net migration are not expected to continue indefinitely because historical patterns indicate that economic peaks eventually return to the mean. Second, the nation's population is aging, which is likely to result in an overall decrease in mobility. Third, current federal immigration policy seems to be moving toward stricter controls and economic conditions in immigrant-sending countries will likely improve. Both factors would make moving to the United States (and Washington) less desirable.

Table 3: Comparison of projected net migration from 2017 and 2011 state forecasts

Period 2010-15 2015-20 2020-25 2025-30 2030-35 2035-40

2017 Forecast 153,283 394,085 266,377 262,200 267,000 248,000

2011 Forecast 104,909 210,000 217,000 225,000 225,000 225,000

Difference Between the 2

Forecasts 48,374 184,085 49,377 37,200 42,000 23,000

Percentage Difference Between

the 2 Forecasts 46.11 87.66 22.75 16.53 18.67 10.22

Methodology and Assumptions

Fertility: Population growth due to births is projected based on forecasted changes to the total fertility rate, or TFR, a measure of the average estimated total number of children born per woman in her reproductive lifetime. For the November 2017 forecast, actual births from 2010 to 2016, along with estimated births for 2017, were incorporated in the model. TFRs for future years were evaluated and updated. Since historically Washington's TFR tracks the national TFR closely, it is

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