Missouri's changing demographic composition presents important challenges for planners and public policy makers. Demands for education, health care, natural resources, and consumer goods and services all are affected by demographic change. Good planning and policy decisions often require up-to-date population projections.
This issue of the Trendletter highlights findings in a new report soon to be published by the Missouri Office of Administration. Projections of the Population of Missouri Counties by Age, Gender and Race: 1990 to 2020 presents three sets of projections based on alternate assumptions about future fertility, mortality and migration. Detailed projections are given by gender for many age groups, including school-age populations, young adults and the elderly. Black and white race detail is also given for selected counties.
Each of the three projection scenarios uses a different assumption about the key migration component. Two scenarios allow observed migration to continue into the future. SCENARIO L, so-labeled for "long-term" migration, carries 1980-1992 county net migration patterns forward. SCENARIO R, so-labeled for "recent" migration, carries 1987-1992 county net migration patterns forward. A third scenario, SCENARIO Z for "zero" migration, illustrates what future county populations would be if births and deaths were the only agents of population change. All scenarios incorporate the same moderate assumptions about future fertility and mortality.
The state's rate of population growth has dropped each decade since 1950. Missouri grew by 9.2 percent in the 1950s, 8.3 percent in the 1960s, 5.1 percent in the 1970s and 4.1 percent in the 1980s. Middle-range growth under Scenario R projects increases of 4.2 percent in the 1990s, 3.4 percent between 2000 and 2010, and 3.1 percent between 2010 and 2020.
State population pyramids for the early part of this century have a shape similar to those for many developing countries today. They are wide at the base for young age groups, and progressively narrower towards the top as higher mortality claims increasing numbers of persons in older age groups.
By 1960, however, the 1960 state pyramid has begun to lose its triangular shape. At the base are very wide bands representing the first large post-war birth cohorts. Just above these bands are narrow bands representing the smaller cohorts born during the Great Depression.
By 1990, the 1990 state pyramid exhibits the distinctive baby-boom bulge of young adults. The bulge is flanked above by expanded bands for older age groups and below by narrow bands for baby-bust children.
All three projection scenarios show that, by 2020, Missouri's pyramid will have a rectangular cast. Baby boomers will swell upper sections of the pyramid to unprecedented widths, and long-sustained low levels of fertility will produce consistent narrow bands in the lower half of the pyramid.
Here is a brief overview of how selected age groups changed over the last thirty years and how they will change over the next thirty years according to Scenario R.
Whether recent or long-term migration trends prevail, the outlook for the next thirty years is one of large growth in the suburban counties around Kansas City, St. Louis and Springfield, and significant decline in agricultural counties. Seven of the top ten fastest-growing counties under Scenario R are metropolitan counties that have strong socioeconomic ties to their central cities but may be located as far as sixty miles away. Christian County, south of Springfield, will more than double in size by 2020. St. Charles County, northwest of St. Louis, will grow by 80 percent. Platte County, northwest of Kansas City, will grow by 69 percent. Other top-ten growth areas include Stone County and Taney County in the Table Rock Lake and music industry boom area around Branson.
With the lone exception of St. Louis City, all ten counties of greatest population decline are rural agricultural counties north of the Missouri River. Knox County and Worth County could lose as much as half of their current populations by 2020. St. Louis City is projected to lose 44 percent of its population under Scenario R.
Migration is the primary agent of population change in these areas of rapid growth and decline, although natural change can compound change. St. Charles County, for example, will gain 96 thousand net inmigrants over the next thirty years under Scenario R, and will gain an additional 75 thousand persons through natural growth. The situation in Knox County is just the opposite. Knox County is projected to lose over two thousand people through migration and an additional three hundred persons through natural decline.
Projection Scenario Z is a useful benchmark series because it shows the effects of fertility and mortality in the absence of migration. Pulaski County, for example, home of the Fort Leonard Wood military post, has a youthful age profile. Its relatively lower mortality and higher fertility rates would produce 38 percent growth between 1990 and 2020 under this scenario.
Hickory County is an opposite example. A rural growth county in the Ozarks, Hickory County has an older age profile associated with the retirement community around Lake Pomme de Terre. Deaths have exceeded births here since the 1960s, and projections show that they will continue to do so. Under Scenario Z, Hickory County would lose 18 percent of its population over the next thirty years. Several rural agricultural and Ozark counties lose population through natural means in all three projection scenarios.
The ten most populous Missouri counties in 1990 and 2020 are listed in Table B. Although St. Louis County and Jackson County are projected to experience slight losses over the next thirty years in both non-zero migration scenarios, they hold their respective number one and two rankings by a wide margin. If net migration were zero, both counties would grow through natural means.
St. Charles County overtakes St. Louis City for the number three ranking in 2020 in both non-zero migration scenarios. Its population nears the 400 thousand mark under each scenario. Like St. Louis County and Jackson County, St. Louis City gains population under Scenario Z. Franklin County, which is projected to grow over three times the state rate in Scenarios L and R, vaults to the 2020 top ten in all scenarios.
The new projections report presents only a fraction of the results from the three projection scenarios. Additional age-gender-race data from Scenarios L and Z are available in machine-readable form, as are all of the tables in the report. For information about ordering machine-readable data and this report, write to: Population Projections, Missouri Office of Administration, P.O. Box 809, Capitol Room 124, Jefferson City, MO 65102.