Life expectancy has dropped slightly for all Americans except for black men, who gained around two and a half months in longevity, a report released Thursday found.
Data gathered by the National Center for Health Statistics showed that life expectancy for most American men was 75.3 years in 2008, down by one-tenth of a year from 2007.
Women also saw a drop in the number of years they can expect to live, from 80.4 years to 80.3 years, the data show.
Black men, on the other hand, bucked the trend and reached a record-high life expectancy of 70.2 years in 2008, up by 0.2 years compared to 2007.
They were still the shortest-lived Americans, though, with life spans around 10 years less than white women, who have the highest life expectancy, followed by black women and white men.
The pattern of white women enjoying the longest lives and black men the shortest has held true for nearly three decades, but life expectancy for all groups has generally increased over those 30 years.
Arialdi Minino, a statistician who worked on the report, told the Washington Post that officials have no idea what may have caused the fall in longevity in 2008.
"I would take this with a grain of salt," he told the Post.
"These are preliminary numbers. You can never tell whether this is a little blip or some trend that will stay there and linger there for some time. You can't tell until you have more data points."
The best state to live in, in terms of mortality, was Hawaii, which had an age-adjusted death rate of 589 deaths per 100,000 people in 2008.
The worst state for mortality was West Virginia, where the age-adjusted death rate was more than one-and-a-half times greater than in Hawaii - 958 per 100,000 people.
Heart disease remained the leading cause of death in the United States, followed by cancer, chronic lower respiratory diseases, stroke and accidental injury.
The sixth leading cause of death was Alzheimer's disease, one of six diseases or causes for which the age-adjusted death rate increased significantly, the study says.
A study released in October said the United States ranked 49th in the world for male and female life expectancy, a precipitous drop from the fifth place it held in 1950.