For instance, in Holmes County, Mississippi, which has the lowest life expectancy in the country, a woman can expect to live 73.5 years, the average life span that women in the healthiest nations had in 1957 and have since far surpassed.
To determine how American life spans stack up internationally, researchers from the U.S. and the U.K. compared life expectancies in the U.S. to a moving average of those in the 10 nations with the lowest death rates, a group that includes other affluent countries such as Switzerland, Australia, Japan, and Canada.
Between 2000 and 2007, the researchers found, more than 80% of U.S. counties fell below the life-expectancy bar set by that group of leading nations, even though the U.S. spends more on health care per capita than any other country in the world.
Given the increasing life expectancy in countries like Canada and Australia, the widespread pattern of decline in the U.S. is "a huge surprise," says Christopher Murray, M.D., one of the study's coauthors and the director of the Institute for Health Metrics and Evaluation at the University of Washington, in Seattle.
"We all know from previous work that there are great [life expectancy] disparities in the U.S. across counties, but I sort of expected that when we compared progress in counties to what's possible that we would be keeping up," Murray says. "And we're not."
The study, which was published in the journal Population Health Metrics, does show huge differences from one U.S. county to the next.
In 2007, life expectancies for men ranged from a high of about 81 years (in Fairfax County, Virginia.) to a low of about 66 years in Holmes County. The trends are especially concerning for women.
Since 1997, women's life expectancy has slipped or failed to rise in more than 850 counties (compared to just 84 counties for men), including 82% of the counties in Oklahoma, 66% in Tennessee, and 59% in Kentucky. In Mississippi, there are five counties where the life expectancy for women is on par with nations such as Honduras, El Salvador, and Peru.
The study's findings are in sync with a report released in January by the National Research Council that compared life spans in the U.S. with those in other high-income nations, says Samuel Preston, Ph.D., a professor of demography at the University of Pennsylvania, in Philadelphia, and a co-chair of the panel that produced that report.
"The conclusion that American women are falling further behind their peers in [leading industrialized countries] certainly is correct, and if it's happening at the national level, it has to be happening in some counties as well," Preston says.
Murray and his coauthors say the county-to-county disparities can't be explained by demographic factors such as income or ethnicity -- even though, for instance, black men and women have lower life expectancies than their white counterparts in all counties.
"Ninety percent of the variation in the pace of progress is not related to either of those factors, so you need to look elsewhere to understand why some counties are keeping up and why other counties are falling behind," Murray says.
The authors suggest that smoking, obesity, high blood pressure, and other behaviors and conditions that contribute to poor health and early deaths might be responsible.
Locally tailored programs that aim to help people quit smoking, lose weight, and otherwise improve their health may help reverse the troubling life-expectancy trends, they say.
"There needs to be more investments in policies and programs at local as well as state and national levels to move those metrics," agrees David Kindig, Ph.D., an emeritus professor of population health sciences at the University of Wisconsin, in Madison, who was not involved in the study.
Kindig adds, however, that it's just as important to invest in programs that, for example, boost education and employment, because social and economic factors also drive health outcomes.
Copyright Health Magazine 2011