The ins and outs of population growth

Last month we covered the basic population changes of Indiana and its 92 counties from 2010 through 2016. Now let’s go deeper to look at the components of population changes: natural increase and domestic and international migration.

Populations grow because, usually, more babies are born than people die. We call that natural increase which accounted for 96 percent of Indiana’s population growth in the years of 2011-16. That means migration (domestic and international) was responsible for just 4 percent of our growth.

Economically, babies are important. They spur people to earn so they can spend on cribs, diapers, larger homes and ultimately education and weddings. Deaths, although important to selected sectors, do not have the wide economic impact of births.

Marion led 70 counties in natural increase with 40,481 more births than deaths. In contrast, among the 22 counties experiencing natural decrease, Henry County (New Castle) led with 572 more deaths than births.

The lowest ratios of deaths to births were in LaGrange (0.35) and Hamilton (0.38) counties, while the highest ratios were in Vermillion (1.32), Brown (1.30) and Fayette (1.27).

When we talk about nations, states, counties or other unnatural divisions of the globe, migration is a key factor in population change. Total migration accounted for only 5,232 persons in the growth of Indiana during the years 2011-16.

However, there was a dramatic difference between net domestic migration and net international migration for Indiana. In the years covered, 56,184 more persons left Indiana for other places in the U.S. than moved to Indiana. This substantial negative flow was counter-balanced by a net international inflow of 61,416 persons.

Only 13 Hoosier counties enjoyed positive net domestic migration totaling 51,587 persons, led by Hamilton County with 20,872. The remaining 79 counties lost a net total of 170,771.

While all these persons moving may seem like a lot, they do not reflect the total number of inter-county migrants because we do not have the detailed data on how many moved from where to where. The Census data say there was net out-migration of more than 19,000 from each of Lake and Marion counties and nearly 6,000 from St. Joseph County. But, how many were just crossing a county line and how many left the state?

Although lacking detail, net international migration seems clearer. Indiana had 82 counties with positive sums of 61,466 persons and only 10 counties with 40 net out-migrants. In Daviess, Jefferson, Tippecanoe, Monroe and Allen counties, positive international migration more than offset negative domestic migration.

In summary, natural increase was the population growth driver in 19 Indiana counties overcoming negative net migration. Only 13 counties were positive in all three components. Every county with natural decrease also had negative domestic migration to result in total population declines.

Now re-read this piece and ask yourself: Is this something we can and should do something about?