Money may not buy you happiness (or love) but it might just buy you more time to find them.

In the most comprehensive look at life expectancy and income—based on tax returns filed by every American from 1999 to 2014—Raj Chetty, professor of economics at Stanford University, and his colleagues report in JAMA that with more income, people tend to live longer. Some experts had expected that at some point, the relationship would level off so that making more wouldn’t provide any added years, but Chetty’s study showed otherwise. While the amount of added life started to shrink as incomes grew, more money essentially lead to more years of life. Overall, people with the top 1% in income lived nearly 15 years longer than those at the bottom 1%.

At the other end of spectrum, lower income was associated with shorter life spans, with no plateau. That suggests that life spans can’t necessarily be traced to something that people are buying to stay alive longer — such as better health care or state-of-the-art drugs. Yes, medical care is important for longevity, but what’s more important, according to this data, are behaviors that can affect health.

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The data also showed interesting differences in life expectancies among those with lower incomes depending on where in the U.S. they lived. While previous studies found that people in urban areas tended to have shorter life spans compared to those living in certain suburban and rural areas, presumably because of the higher cost of living in cities and the added stress of being in a densely populated area, Chetty found the opposite to be true. In fact, lower income people living in cities like New York and San Francisco enjoyed longer life expectancies than those living in Detroit or Tulsa.

While it’s not clear why, Chetty suspects that there is a trickle-down effect in certain cities where public health efforts to improve living conditions, enforce policies like smoking bans and removal of unhealthy ingredients like trans fats benefit people at all income levels. People with lower incomes in cities with such policies tended to be less obese, smoke less and have better health behaviors than people in other cities that didn’t advocate for such health-promoting behaviors. “Inequalities in life expectancy across areas are more likely explained by different behaviors rather than access to life-saving medical care,” says Chetty.

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By analyzing data at the local level, he was able to discern differences in life expectancy that national level data don’t pull out. And that’s important for understanding how public health officials can start to bring some of the benefits to people in other income brackets as well. “The big picture message is that there is a lot of talk about inequality at a national level, but this paper shows that in the context of health, for one of the most important outcomes, life expectancy, the debate should be a local one,” says Chetty.

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