In affluent West Bellevue, residents enjoy King County’s highest life expectancy — nearly a decade longer than those living in economically challenged South Auburn.

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It only takes about half an hour to drive from Bellevue to Auburn.

But there’s a gulf between the residents of those two cities that is 10 years wide. That’s the difference in how long they can expect to live.

In affluent West Bellevue, folks enjoy the highest life expectancy in King County — 86.2 years, according to public-health data derived from death records. The county’s shortest life span is in economically challenged South Auburn, at just 76.6 years.

The gap in life expectancy between rich and poor is well established — and it’s been growing in recent years, according to a sweeping national study published last week in The Journal of the American Medical Association.

Income, however, is just one component determining length of life. The study, led by Stanford University economist Raj Chetty, reveals that another factor may be even more important: place.

For example, poor people in walkable big cities — like San Francisco and New York, with smoking bans and strong tax bases to fund services — live significantly longer than their counterparts in poorer places.

According to data from the study, people in the lowest income bracket in King County have a life expectancy of 80.5 years. That’s about one year longer than the national average, and ranks King 30th among the 100 largest counties.

But there’s a lot of variability in health outcomes within the county, says Health Officer Jeff Duchin at Public Health — Seattle & King County. “You really need to understand this issue at a more granular level.”

Which is what the public health department has done, dividing the county into 48 “Health Reporting Areas.”

Data collected at this community level show that places such as Auburn, with its much shorter life expectancies, also have higher levels of adverse health outcomes: smoking, cardiovascular disease, hypertension and other chronic diseases.

“We see these things clustered by geography,” Duchin said. “Ultimately, your ZIP code is more important than your genetic code when it comes to health outcomes.”

Public-health officials used to think that a community’s health outcomes were primarily tied to access to health care. That thinking has changed.

The health of a community’s population, Duchin says, is influenced by many characteristics — quality of housing and education, job opportunities, access to healthful food, neighborhood safety and green spaces, for example.

Public-health officials are working to close the county’s 10-year gap in life expectancy by addressing these drivers of health outcomes, Duchin says. Some major initiatives are under way, including Communities of Opportunities and voter-approved Best Start for Kids.

Anyone who lives in King County is aware of the economic inequities — particularly between the south part of the county and wealthier areas to the north. But expressing that disparity in terms of a shortened life span gives it a powerful reality, Duchin has found.

“People are flabbergasted when I show them the 10-year gap in life expectancy between some areas of south county and the Eastside — that really hits home,” he said.

“The more people understand how various factors drive health outcomes and life expectancy, the more people want to fix that problem.”