MONDAY, May 8, 2017 (HealthDay News) -- How long you will live depends a lot on where you live in the United States, a new study of federal health data reveals.
Overall, life expectancy increased for American men and women by slightly more than five years between 1980 and 2014, researchers report.
But life span can differ by as much as two decades between various U.S. counties, said lead researcher Ali Mokdad, a professor of global health with the University of Washington's Institute for Health Metrics and Evaluation, in Seattle.
"You have people here in this country that are living longer than the life expectancy of the best country in the world, and you have people here in certain counties who have a life expectancy similar to some developing countries in the Middle East or South America or Cuba, for example," Mokdad said.
Economic and lifestyle factors appear to account for much of the gap, Mokdad added.
A group of counties in central Colorado -- which include affluent cities like Aspen and Breckenridge -- have the nation's highest life expectancy, the researchers found.
Summit County, Colo., topped the list at 86.8 years, followed by Pitkin County (86.5 years) and Eagle County (85.9 years).
That's better than the principality of Andorra, a tiny country wedged between France and Spain that has the world's longest life expectancy at 84.8 years, the researchers said. Iceland has the next highest life expectancy among countries, at 83.3 years.
On the other hand, several counties in North and South Dakota containing Native American reservations had the lowest life expectancy in the United States, the researchers found. And Southern counties along the lower half of the Mississippi, in eastern Kentucky, and in southwestern West Virginia also had very low life expectancy.
Oglala Lakota County, S.D., which includes the Pine Ridge Native American reservation, had the lowest life expectancy in the country in 2014 at 66.8 years -- comparable to countries like Sudan (67.2 years), India (66.9 years) and Iraq (67.7 years), the researchers said.
Overall, life expectancy in the United States increased for men and women a combined 5.3 years, from 73.8 years to 79.1 years. For men, life expectancy rose from 70 to 76.7 years, while for women it rose from 77.5 to 81.5 years.
But this average increase was fueled by large increases in life expectancy in certain parts of the country, such as central Colorado, western California and along the East Coast. In other parts of the country -- most notably eastern Kentucky, central Alabama and southwestern Oklahoma -- there were some counties where life expectancy actually fell by one to two years.
The researchers compensated for three main differences between U.S. counties -- economic conditions, known health risk factors, and quality of health care -- to see why some areas experienced a huge increase in life expectancy while others didn't, Mokdad said.
Health risk factors appear to play the largest role in a county's life expectancy, with 74 percent of the difference explained by things like physical activity, diabetes, blood pressure, smoking and obesity, Mokdad said.
"If you level the playing field when it comes to these risk factors, you can eliminate 74 percent of disparities," Mokdad said.
The economic and racial makeup of an area explains 60 percent of the variation in life expectancy, the researchers found, while quality and availability of health care accounts for just 27 percent of the life expectancy gap.
The findings were published May 8 in the journal JAMA Internal Medicine.
These numbers show that an environment that promotes healthy living has more of an impact on how long you'll live than the kind of health care available to you, Mokdad said.
"We're not going to get out of this investing solely in the medical system," Mokdad stressed. "We have to invest in prevention."
Another public health expert agreed.
Communities that are more walkable, have better access to healthy foods, and benefit from strong public health efforts create an environment that can extend a person's life, said Laura Hanen. She is chief of government affairs for the National Association of County & City Health Officials.
Bike share programs, park improvements, community gardens and farmers' markets are all steps that an area can take to improve the health of residents, Hanen said.
"You're trying to create a culture of health, so the healthy choice is the easy choice," Hanen said, adding that the "vast majority of what impacts health is everything that happens outside of a doctor's office."
However, Hanen noted these policies are more difficult to implement in poorer rural areas with a spread-out population. "In a large urban area, you can make changes that will impact a much greater number of people," she said.
For more on life expectancy, visit the U.S. National Institute on Aging.