Life expectancy in the U.S. varies by more than 20 years depending on what county someone lives in, according to a new report in JAMA Internal Medicine. University of Washington researchers found the gap between counties grew from 1980 to 2014 and predicted the trend will continue.

Why it matters: Public health experts have said our zip code determines our health more than our genetic code — these findings show just how big the gap is, and that it is widening. Poverty, education, and unemployment as well as smoking, lack of exercise and access to quality health care explained 75% of the difference in life expectancy, illustrating there are many interconnected levers to pull in shaping health policy.

Reproduced from 'Inequalities in Life Expectancy Among US Counties, 1980 to 2014: Temporal Trends and Key Drivers'

Best and worse places: Central Colorado counties had the highest life expectancy (87 years) in 2014. North and South Dakota counties encompassing Native American reservations had the lowest-- 66 years.

Where things got worse: Life expectancy grew 5.1 years overall but in some places it actually fell between 1980 and 2014. 8 of the 10 counties with the largest declines in life expectancy are in Kentucky.