Asian-American women living in Bergen County, N.J., lead the nation in longevity, typically reaching their 91st birthdays. Worst off are American Indian men in swaths of South Dakota, who die around age 58 - three decades sooner.

Millions of the worst-off Americans have life expectancies typical of developing countries, concluded Dr. Christopher Murray of the Harvard School of Public Health.

Asian-American women can expect to live 13 years longer than low-income black women in the rural South, for example. That's like comparing women in wealthy Japan to those in poverty-ridden Nicaragua.

Compare those longest-living women to inner-city black men, and the life-expectancy gap is 21 years. That's similar to the life-expectancy gap between Iceland and Uzbekistan.

Health disparities are widely considered an issue of minorities and the poor being unable to find or afford good medical care. Murray's county-by-county comparison of life expectancy shows the problem is far more complex, and that geography plays a crucial role.

"Although we share in the U.S. a reasonably common culture ... there's still a lot of variation in how people live their lives," explained Murray, who reported initial results of his government-funded study in the online science journal PLoS Medicine.

Consider: The longest-living whites weren't the relatively wealthy, which Murray calls "Middle America." They're edged out by low-income residents of the rural Northern Plains states, where the men tend to reach age 76 and the women 82.

Yet low-income whites in Appalachia and the Mississippi Valley die four years sooner than their Northern neighbors.

He cites American Indians as another example. Those who don't live on or near reservations in the West have life expectancies similar to whites'.

"If it's your family involved, these are not small differences in lifespan," Murray said. "Yet that sense of alarm isn't there in the public."

"If I were living in parts of the country with those sorts of life expectancies, I would want ... to be asking my local officials or state officials or my congressman, 'Why is this?'"

This more precise measure of health disparities will allow federal officials to better target efforts to battle inequalities, said Dr. Wayne Giles of the Centers for Disease Control and Prevention, which helped fund Murray's work.

The CDC has some county-targeted programs, like one that has cut in half diabetes-caused amputations among black men in Charleston, S.C., since 1999, largely by encouraging physical activity and the new study argues for more, he said.

"It's not just telling people to be active or not to smoke," Giles said. "We need to create the environment which assists people in achieving a healthy lifestyle."

The study also highlights that the complicated tapestry of local and cultural customs may be more important than income in driving health disparities, said Richard Suzman of the National Institute on Aging, which co-funded the research.

"It's not just low income," Suzman said. "It's what people eat, it's how they behave, or simply what's available in supermarkets."

Murray analyzed mortality data between 1982 and 2001 by county, race, gender and income. He found some distinct groupings that he named the "eight Americas:"

- Asian-Americans, average per capita income of $21,566, have a life expectancy of 84.9 years.

- Northland low-income rural whites, $17,758, 79 years.

- Middle America (mostly white), $24,640, 77.9 years.

- Low income whites in Appalachia, Mississippi Valley, $16,390, 75 years.

- Western American Indians, $10,029, 72.7 years.

- Black Middle America, $15,412, 72.9 years.

- Southern low-income rural blacks, $10,463, 71.2 years.

- High-risk urban blacks, $14,800, 71.1 years.

Longevity disparities were most pronounced in young and middle-aged adults. A 15-year-old urban black man was 3.8 times as likely to die before the age of 60 as an Asian-American, for example.

That's key, Murray said, because this age group is left out of many government health programs that focus largely on children and the elderly.

Moreover, the longevity gaps have stayed about the same for 20 years despite increasing national efforts to eliminate obvious racial and ethnic health disparities, he found.

Murray was surprised to find that lack of health insurance explained only a small portion of those gaps. Instead, differences in alcohol and tobacco use, blood pressure, cholesterol and obesity seemed to drive death rates.

Most important, he said, will be pinpointing geographically defined factors, such as shared ancestry, dietary customs, local industry, what regions are more or less prone to physical activity that in turn influence those health risks.

For example, scientists have long thought that the Asian longevity advantage would disappear once immigrant families adopted higher-fat Western diets. Murray's study is the first to closely examine second-generation Asian-Americans, and found their advantage persists.

The 25 counties with the highest and lowest life expectancy, according to a study in the online science journal PLoS Medicine:

Highest life expectancy

County Life Expectancy

Clear Creek, Colo. 81.3

Eagle, Colo. 81.3

Gilpin, Colo. 81.3

Grand, Colo. 81.3

Jackson, Colo. 81.3

Park, Colo. 81.3

Summit, Colo. 81.3

Montgomery, Md. 81.3

Lyon, Iowa 81.3

Sioux, Iowa 81.3

Nicollet, Minn. 81.1

Story, Iowa 81.0

Carver, Minn. 81.0

Collier, Fla. 81.0

Benton, Ore. 80.9

Polk, Ore. 80.9

Fairfax City, Va. 80.9

Fairfax County, Va. 80.9

La Paz, Ariz. 80.9

Yuma, Ariz. 80.9

Winneshiek, Iowa 80.8

Morgan, Utah 80.8

Summit, Utah 80.8

Archuleta, Colo. 80.8

Gunnison, Colo. 80.8

Lowest life expectancy

Washabaugh, S.D. 66.6

Todd, S.D. 66.6

Shannon, S.D. 66.6

Mellette, S.D. 66.6

Jackson, S.D. 66.6

Bennett, S.D. 66.6

Baltimore City, Md. 68.6

Petersburg, Va. 69.6

Marlboro, S.C. 69.6

Phillips, Ark. 69.8

Coahoma, Miss. 70.1

Union, Fla. 70.2

Baker, Fla. 70.2

Mcdowell, W.Va. 70.4

St. Louis City, Mo. 70.8

Pemiscot, Mo. 70.9

Sunflower, Miss. 71.1

Crittenden, Ark. 71.1

Richmond City, Va. 71.1

Washington, Miss. 71.1

Tunica, Miss. 71.2

Tallahatchie, Miss. 71.2

Quitman, Miss. 71.2

Logan, W.Va. 71.2

Martin, N.C. 71.2

Life expectancy by state, according to a study in the online science journal PLoS Medicine:

State Life expectancy Rank

Ala. 74.4 48

Alaska 77.1 26

Ariz. 77.5 22

Ark. 75.2 43

Calif. 78.2 10

Colo. 78.2 12

Conn. 78.7 4

Del. 76.8 29

D.C. 72 51

Fla. 77.5 21

Ga. 75.3 41

Hawaii 80.0 1

Idaho 77.9 15

Ill. 76.4 33

Ind. 76.1 37

Iowa 78.3 7

Kan. 77.3 24

Ky. 75.2 42

La. 74.2 49

Maine 77.6 20

Md. 76.3 35

Mass. 78.4 5

Mich. 76.3 34

Minn. 78.8 2

Miss. 73.6 50

Mo. 75.9 38

Mont. 77.2 25

Neb. 77.8 16

Nev. 75.8 39

N.H. 78.3 6

N.J. 77.5 23

N.M. 77.0 27

N.Y. 77.7 19

N.C. 75.8 40

N.D. 78.3 8

Ohio 76.2 36

Okla. 75.2 44

Ore. 77.8 17

Pa. 76.7 31

R.I. 78.3 9

S.C. 74.8 47

S.D. 77.7 18

Tenn. 75.1 45

Texas 76.7 30

Utah 78.7 3

Vt. 78.2 11

Va. 76.8 28

Wash. 78.2 13

W.Va. 75.1 46

Wis. 77.9 14

Wyo. 76.7 32