A new study from Yale School of Public Health reveals stark variations in life expectancy across U.S. states over the past century, linking public health policies, socioeconomic factors and environmental conditions to lifespan disparities.
Researchers at the Yale School of Public Health (YSPH) have uncovered significant disparities in life expectancy across U.S. states, exposing the profound influence of regional public health policies, social conditions and environmental factors on lifespans.
The comprehensive study, published in JAMA Network Open, analyzed over 179 million deaths from 1969 to 2020.
By examining life expectancy trends by birth cohort, the researchers were able to more accurately capture how the lives of different generations have been shaped over time.
“For females born in some Southern states, life expectancy increased by less than three years from 1900 to 2000,” lead author Theodore R. Holford, the Susan Dwight Bliss Professor Emeritus of Biostatistics at YSPH, said in a news release. “That’s a staggering contrast when you consider that in states like New York and California, life expectancy rose by more than 20 years over the same period.”
States in the Northeast and West, along with Washington, D.C., recorded the greatest gains in life expectancy. The nation’s capital, which had the lowest life expectancy for the 1900 birth cohort, saw improvements of 30 years for females and 38 years for males by 2000.
Meanwhile, states like Mississippi, Alabama and Kentucky exhibited minimal gains, particularly among women.
“These trends in mortality and life expectancy reflect not only each state’s policy environment but also their underlying demographics as well,” added co-author Jamie Tam, an assistant professor of health policy and management at YSPH. “It’s not surprising that states with fewer improvements to life expectancy also have higher rates of poverty, for example.”
The research team employed an age-period-cohort model, a sophisticated method enabling them to untangle the effects of aging, historical events and generational influences on mortality. This approach revealed how early-life exposures — such as access to sanitation, vaccinations or tobacco — impacted health trajectories later in life.
“Looking at mortality trends by cohort gives us a more accurate reflection of the lived experiences of populations,” Holford added. “It shows the long-term impact of policies and social conditions affecting the life course of populations that might otherwise be invisible in year-by-year comparisons of mortality rates from different generations..”
Additionally, the researchers examined the rate at which mortality increased after age 35. Longer doubling times, which indicate healthier aging, varied significantly across states, with New York and Florida showing slower increases and Oklahoma and Iowa displaying faster escalations.
Holford pointed out that these patterns represent more than a historical record.
“The disparities we see today are the result of decades of cumulative effects — on smoking rates, health care access, environmental exposures and public health investments,” he added. “Without conscious policy changes, these gaps will likely persist or even widen.”
The study also highlighted the influence of local health policies using California and Kentucky as examples. California’s early adoption of smoke-free workplace policies in 1995 led to significant reductions in smoking rates and, consequently, improved mortality rates. Conversely, Kentucky’s lack of similar initiatives contributed to higher smoking rates and increased mortality.
“Where you are born shouldn’t determine how long you live. But in America, it still does,” Holford added.
The researchers hope their findings will prompt a greater focus on interventions — such as tobacco control, improved health care access and environmental protections —that can improve life expectancy outcomes for future generations.
“This research highlights the importance of viewing health through a generational lens,” Tam added. “The benefits of health interventions ripple across lifetimes.”
Source: Yale School of Public Health