|Understanding Illinois’ loss of prime working-age adults
The Census Bureau migration data provide aggregate totals of domestic migration and international immigration each year for each state. In order to understand who is leaving and why, it is necessary to examine closely the age cohorts of people who are leaving.
This can be done by considering the population of a given age group of Illinoisans in 2005, and then looking at the same population group again in 2015 after the group members have aged 10 years.
For example, BLS data show Illinois had 1.75 million adults in the 25-34 age cohort in the year 2005. Looking forward to 2015, these 1.75 million 25-34-year-olds should make up the entire age group of the 35-44 age bracket. Assuming nothing changes on the migration front, by the year 2015 Illinois would have 1.73 million adults in the 35-44 age bracket after the 25-34 age cohort has aged a decade. The slight decrease in population is based on the mortality assumption of 16,400 deaths from this age cohort using Centers for Disease Control and Prevention mortality data. Only net gains or losses from migration would make this number move from the expected 1.73 million.
The BLS data for Illinois’ 25-34-year-old age cohort from 2005 reveal that only 1.53 million of them remained in Illinois by 2015. That means that Illinois lost 216,000 adults from this prime working-age cohort between 2005 and 2015, with the majority of that population loss attributable to migration. The same pattern appears true of the other age cohorts that make up Illinois’ current prime working-age population. Over the past decade, Illinois lost a net of 12,000 people from its current 25-34-year-old age cohort, 216,000 from its current 35-44-year-old age cohort, and 126,000 from its current 45-54-year-old age cohort.
All told, BLS data show Illinois had a net loss of 354,000 adults over the last decade from its current prime working-age adult population (ages 25 to 54), with 290,000 of that loss attributable to migration rather than mortality.