Why are Eighth District Populations Growing More Slowly than the Rest of the U.S.?

In recent years, U.S. population growth has slowed significantly due to falling birth rates, rising death rates and fewer immigrants coming into the country. See Emmons, Bill, “U.S. Population Growth Slowing to a Crawl,” On the Economy, Feb. 2020. Similar to the rest of the nation, population growth rates in all seven states within the Eighth District (Arkansas, Illinois, Indiana, Kentucky, Mississippi, Missouri and Tennessee) have recently declined (see Figure 1).

Differences in migration rates (domestic and international), rather than divergent trends in birth or death rates, are the largest source of variation in population growth among the district’s seven states. More precisely, relatively low rates of inward net migration are the main reason Eighth District states grow more slowly than the U.S. as a whole.

Figure 1 shows that beginning in 2012, more people have moved out of Eighth District states than moved in.

Given the long-term slowing of natural population increase (i.e., births minus deaths), migration trends are becoming increasingly important in determining which counties, metro areas and states gain and lose population. Historically, our district’s states have not always been deemed areas of peak migration; however, areas within Tennessee have attracted large numbers of domestic migrants, while Illinois has been a destination for international migration.

With advantages like a low cost of living, Eighth District state populations may be bolstered by migration in the future.

A Primer on Sources of Population Growth

Population in a particular place grows or declines for two reasons:

1. Natural increase (births minus deaths).
2. Net migration (the number of people moving to a place minus the number of people who move away).

For entities smaller than the nation as a whole, net migration is divided between net domestic migration (inward minus outward moves within the U.S.) and net international migration (immigration into the area from outside the U.S. minus emigration from the place to somewhere outside the U.S).

Sources of Population Growth Vary Widely

The sources of recent individual state population slowing differ significantly.

• More death rates have increased in Kentucky and Mississippi than elsewhere in the District and nation.
• Domestic migration into Arkansas and Kentucky, while positive in most years, has declined.
• Domestic migration in Illinois and Mississippi has increased.
• International migration, a slightly larger contributor to population growth in Illinois, recently fell below the national rate.

Additionally, some trends have worked in favor of Eighth District state population growth:

• Indiana’s population growth rate has surpassed the national rate due to slightly more favorable trends in the birth rate and both domestic and international migration.
• Arkansas, Kentucky, Missouri and Tennessee all experienced slightly better birth rate trends (i.e., slower declines) than the nation as a whole.
• Tennessee’s high domestic migration rate rebounded in recent years after a post-recession slowdown.

When all sources of change are considered, five states within the Eighth District continue to grow more slowly than the nation (Arkansas, Illinois, Kentucky, Mississippi and Missouri), while two states are growing faster than the nation (Indiana and Tennessee).

How Our States Grow

The easiest way to see how various aspects of natural increase and net migration contribute to a state’s total population growth is to display them relative to the nation as a whole.

In other words, each factor can be shown contributing more to the state’s population growth in a given year than it does at the national level or less. The sum of the contributing factors is the annual difference between the state’s and the nation’s population growth rates.

Figures 2-8 display features of each Eighth District state’s developments from 2001-2019, summarized below.

Arkansas (Figure 2). Domestic migration was a major contributor to above-average population growth in the mid-2000s, especially in the northwest part of the state, but it subsided after 2011. Natural increase has been slowing growth relative to the U.S. throughout the period. International migration also has been weaker than the national average, slowing population growth.

Illinois (Figure 3). The dominant factor throughout the period is negative domestic migration, which became even more negative after 2010. Natural increase was close to the national average throughout the period. International migration changed from a small positive to a small negative over time, relative to the U.S. as a whole.

Indiana (Figure 4). Both domestic and international migration changed from being small negative to small positive factors over time. Natural increase moved from being a minor negative factor to approximately neutral by the end of the period. The result is that Indiana’s population growth has recently exceeded the national average.

Kentucky (Figure 5). Domestic migration was a significant factor offsetting the negative influence of the natural increase in the 2000s, but became a minor detractor after 2011. Natural increase and international migration remained negative contributors throughout the entire period, pushing the state’s population growth below the national average.

Mississippi (Figure 6). The only factor that contributed positively in every year was the birth rate; but, in most years, the overall rate of natural increase subtracted from growth due to above-average death rates. Hurricane Katrina caused a large, one-time loss of population through outward domestic migration. Total net migration (domestic and international) was negative in every year, largely causing the state’s below-average population growth.

Missouri (Figure 7). Above-average domestic migration contributed positively in the mid-2000s but reversed after 2007, placing downward pressure on the growth rate. Natural increase and international migration have been negative contributors throughout the period.

Tennessee (Figure 8). Domestic migration was above the national average in every year, with cyclical peaks in 2006 and 2017. All other factors contributed negatively in virtually every year. Without the contribution of domestic migration, population growth would have been significantly below the national average throughout the period; yet, it was above-average.

Migration Patterns Will Determine Population Growth and Decline

Due to declining birth rates and increasing death rates, the amount of natural population increase is slowing nationwide and in each of our District states. The most important contributors to population growth or decline in particular locations will be migration patterns, both domestic and international.

While states in the Eighth District generally have not been net attractors of migrants, Tennessee and a few other states have periodically been exceptions to this rule. Desirable features such as our low cost of living may help some localities resist the population growth slowdown that is underway.

William R. Emmons is an assistant vice president and economist at the Federal Reserve Bank of St. Louis and the lead economist for the Bank's Center for Household Financial Stability.