With the exception of one city (Baltimore), the counties with shortest life expectancy at birth have a largely rural population.
The three counties in West Virginia on the list also have economies formerly dominated by coal.
Ten of the counties on the list, 9 of them with majority non-Hispanic white populations, experienced declines in life expectancy between 1980 and 2014.
The residents of Summit County, Colorado live an average of 86.83 years.
[1] A study published in the Journal of the American Medical Association in 2016 concluded that income was a major component of the difference in life expectancy in states, counties, races, and regions of the U.S. Men in the richest one percent of the population lived 15 years longer than men in the poorest one percent of the population.