Race, Income, Geography Influence Lifespan

How race, income, and geography influence US life expectancy:

Researchers at Harvard University's Initiative for Global Health and its School of Public Health divided the US into eight "Americas" based on factors including race, location, population density, income and homicide rates:

• Asians, 10.4 million popuulation, $21,566 average income, life expectancy 84.9 years;
• Northland low-income rural whites, 3.6 million population, $17,758 average income, life expectancy 79 years;
• Middle Americans, 214 million population, $24,640 average income, life expectancy 77.9 years;
• Low-income whites in Appalachia and Mississippi, 16.6 million population, $16,390 average income, life expectancy 75 years;
• Western Native American, 1 million, $10,029 average income, life expectancy 72.7 years;
• Black middle America, 23.4 million population, $15,412 average income, life expectancy 72.9 years;
• Southern, rural, low-income black, 5.8 million population, $10,463 average income, life expectancy 71.2 years; and
• High-risk urban black, 7.5 million population, $14,800 average income, life expectancy 71.1 years.

The primary cause of the disparities between racial and geographic groups is early death from chronic disease and injuries, an analysis of data from the Census Bureau and the National Center for Health Statistics showed.

Asian-American women living in Bergen County, NJ, enjoy the greatest life expectancy in the US, at 91 years. American Indians in South Dakota have the worst, at 58 years.

I wonder which effects are due to cultural habits, environment, education, diet, genetics, and income?  I'm also curious if there are differences in the gender gap between different racial and geographical groups?  Also, which groups experience the greatest variance in these averages?

I've had Japanese friends tell me that the Japanese health care system is superior to that in the US and that is responsible for their longer average lifespans.  Interestingly, it looks like Asians live longer in the US on average than they do back home...

See the Harvard study here.