The United States ranks below dozens of other high-income countries in life expectancy, according to the World Bank. It is highest in Japan, at nearly 84 years.
The CDC report is based mainly on 2015 death certificates. There were more than 2.7 million deaths, or about 86,000 more than the previous year. The increase in raw numbers partly reflects the nation's growing and aging population.
It was led by an unusual upturn in the death rate from the nation's leading killer, heart disease. Death rates also increased for chronic lower lung disease, accidental injuries, stroke, Alzheimer's disease, diabetes, kidney disease and suicide.
The only clear drop was in cancer, the nation's No. 2 killer.
Experts aren't sure what's behind the stall. Some, like Olshansky, suspect obesity, an underlying factor in some of the largest causes of death, particularly heart disease.
But there's also the impact of rising drug overdoses and suicides, he noted. "There are a lot of things happening at the same time," he said.