How changes in components of growth affect the population aging of states

We analyzed the demographic determinants of population aging for states of the United States between 1950 and 1980. Using the factorial projections method, we estimated the effects of population momentum and changes in mortality, fertility, and migration on changes in the proportion of persons age 65+. Declining mortality rates caused the population to age in virtually every state in every decade between 1950 and 1980, but the effects were very small. The effects of changes in fertility rates were considerably greater. Population momentum generally had a greater effect on population aging than changes in either fertility or mortality rates. Net migration was by far the most volatile component of population aging, both in terms of changes over time and state-to-state differences at a given point in time. We expect this trend to continue in coming decades.