Does the income have any relationship with life expectancy?

 In the United States, National Library of Medicine has investigated whether the income has any kinds of relationship with life expectancy between 2001 and 2014. As a result, higher income was associated with greater longevity, and differences in life expectancy across income groups increased. However, the association between life expectancy and income vacried substantially across areas; differences in longevity across income groups decreased in some areas and increased in others. The differences in life expectancy were correlated with health behaviors and local area characteristics.

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