Life-Expectancy Gap by Age

What you're seeing. Each county's life expectancy at birth is compared with the United States, and the gap is split across age groups by an Arriaga decomposition — the standard demographic method for asking which ages a life-expectancy difference comes from. These are the very same numbers behind the Life Expectancy page: open any county's life table there and the “Ahead of / Behind the U.S. at…” lines are this decomposition, summarized.

How to read one row. Take Baltimore city, MD — its life expectancy is 6.1 years below the U.S. Read across the age bands: the −1.8 at 55–64 means mortality in that age range alone pulls Baltimore 1.8 years below the U.S.; the −1.3 at 45–54 costs another 1.3, and so on. Add the ten bands and they equal −6.1 — that is the whole point of the method: the age pieces sum exactly to the total gap, so you can see not just how far behind a place is but where the years are lost.

Signs and color. Green (+) means the county does better than the U.S. at that age; amber (−) means worse. Deeper color is a bigger effect; bands within about a quarter-year of the U.S. stay gray.

A subtlety worth knowing. Some hard-hit counties show a small green at 85+ even while deep amber through midlife. That is a survivor effect: where midlife mortality is very high, the few who reach old age are an unusually hardy, selected group, so their death rate can fall below the national one. It is not a sign that elders are thriving — it means the gap was already paid earlier in life.

Method: Arriaga, E.E. (1984), “Measuring and explaining the change in life expectancies,” Demography 21(1). Contributions are years of life expectancy, decomposed by 5-year age group and collapsed to the ten bands shown; life tables from CDC WONDER mortality, computed on DemographyInfo.org.