Although life expectancy overall has improved in the U.S. in the past decade, a troubling new study by the University of Washington, published in Population Health Metrics on June 15th, reveals that the U.S. is starting to lag behind other developed nations. The LA Times also published a feature on the shocking study.

Between 1997 and 2007, in 737 counties (out of 3,147) in the United States, life expectancy for women actually declined, creating a growing gap between the longest life expectancies and the lowest in the nation. This is a rare and disturbing phenomenon in a developed country. Researchers believe that preventable factors, such as smoking, high blood pressure, and obesity, are partly to blame. The national rate of obesity has more than doubled from 1980 to 2010, with 34% of Americans now classified as obese.

Poverty was a factor in lower life expectancies for both men and women, with the lowest life expectancies in poor, rural areas in the South, the lower Midwest, the Appalachia regions, and urban centers. In some counties, life expectancies for women had dropped by as much as a year between 1997 and 2007 (and in the case of Madison County, Mississippi, by a whopping 2.5 years!).

Five counties in Mississippi had the lowest life expectancies for women, at below 74.5 years. Four of those counties also had the lowest life expectancies for men at 67 years. Life expectancies in these counties are lagging behind countries such as Peru, Honduras, and El Salvador.

The growing gap between areas where people had the highest and the lowest life expectancies was also apparent. Within some states, there was a gap of as much as 10 years between the counties with the highest life expectancies and the lowest. Affluent areas, such as Washington D.C. and the San Francisco Bay Area, boasted among the highest life expectancies in the world.

Puzzlingly, Los Angeles County, which has relatively high poverty rates, showed among the highest life expectancies in the country. Experts believe that perhaps high numbers of Latino immigrants may play a role in this phenomenon, perhaps due to healthier diets, better social networks, and better health in general.

Although the overall life expectancy for men and women has improved in the U.S. during the past decade, we have begun to trail other developing nations, dropping to 35th on the list of highest life expectancies in the world (down from 20th in 1987). This is despite paying more per capita on health care than any other nation in the world.