Study Reveals Stark Differences in Life Expectancy Across U.S. States Over the Past Century

A sweeping new study led by researchers at the Yale School of Public Health (YSPH) reveals striking disparities in life expectancy across U.S. states and the District of Columbia over the past century. The study provides new insights into how public health policies, social conditions, and environmental factors appear to have fundamentally shaped Americans’ longevity based on where they live.

Analyzing more than 179 million deaths between 1969 and 2020, the multi-institutional research team traced life expectancy trends by birth cohort — a more precise measure for following the life experience of a population than traditional year-by-year summaries of mortality, which represent a mix of many generations.

Their findings paint a sobering picture: while some states saw dramatic gains in life expectancy, others, particularly in the South, experienced little or no improvement over an entire century.

“For females born in some Southern states, life expectancy increased by less than three years from 1900 to 2000,” said the study’s lead author Dr. Theodore R. Holford, PhD ’73, Susan Dwight Bliss Professor Emeritus of Biostatistics at YSPH. “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.”

The researchers found that states in the Northeast and West, along with the District of Columbia (D.C.), recorded the greatest gains. Notably, D.C. had the lowest life expectancy for the 1900 birth cohort but achieved an improvement of 30 years for females and 38 years for males by 2000 — a testament to urban policy shifts and changing demographics.

By contrast, states like Mississippi, Alabama, and Kentucky saw minimal gains, particularly among women, suggesting that systemic factors — including socioeconomic disadvantages, limited access to health care, and weaker public health initiatives — have left lasting imprints on mortality.

“These trends in mortality and life expectancy reflect not only each state’s policy environment, but also their underlying demographics as well,” said Dr. Jamie Tam, PhD, MPH, an assistant professor of health policy and management at YSPH and a study co-author. “It’s not surprising that states with fewer improvements to life expectancy also have higher rates of poverty for example.”

The research team included biostatisticians, epidemiologists, and health policy experts from Yale, the University of Michigan, and the University of British Columbia, reflecting the multidisciplinary nature of the study.

The researchers used an age-period-cohort model, allowing them to disentangle the effects of aging, historical events that affect all ages at a particular time, and generational influences on mortality. This method captured how early-life exposures—such as access to sanitation, vaccinations, or tobacco—shaped health trajectories later in life.

“Looking at mortality trends by cohort gives us a more accurate reflection of the lived experiences of populations,” Holford explained. “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.”

The disparities revealed by the study are stark. For men born after 1950 in many Southern states, life expectancy gains essentially plateaued, with increases of less than two years thereafter. Meanwhile, states like Hawaii and Massachusetts consistently topped the rankings for both men and women.

The team also examined the rate at which mortality increased after age 35, which is summarized by the number of years it takes for an individual’s risk of death to double. Longer doubling times indicate healthier aging. Again, regional differences were clear: New York and Florida showed slower mortality increases, while Oklahoma and Iowa saw faster mortality escalations.

Holford emphasized that these patterns are not simply historical artifacts. “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 said. “Without conscious policy changes, these gaps will likely persist or even widen.”

The researchers hope their findings will inform policymakers, especially as debates continue over how best to address widening health inequities across the United States.

“This research highlights the importance of viewing health through a generational lens,” added Tam. “The benefits of health interventions ripple across lifetimes. California, for example, was an early adopter of progressive public health policies, like smoke-free air laws, which contributed to its substantial health gains. States with fewer tobacco regulations are still facing higher mortality rates from smoking-related illnesses. So, a failure to act early and invest in public health harms future generations as well.”

Tam is affiliated with the Yale Cancer Center and a co-investigator with Yale’s Cancer Intervention and Surveillance Modeling Network (CISNET). She was previously a NAM Tobacco Regulatory Science Fellow at the FDA Center for Tobacco Products and was recently recognized as the 2023 recipient of the Society for Research on Nicotine and Tobacco Jarvik-Russell Early Career Award.

The current study appears in JAMA Network Open.

The research was funded by the National Institutes of Health and underscores the Yale School of Public Health’s leadership in applying sophisticated statistical modeling to tackle pressing public health challenges.

Holford and Tam hope their findings encourage greater focus on upstream interventions — like tobacco control, health care access, and environmental protections — that can transform life expectancy outcomes for future generations.

As Holford put it, “Where you are born shouldn’t determine how long you live. But in America, it still does."

Artificial intelligence software assisted with the creation of this article.