LOS ANGELES, June 20 (Xinhua) -- The overall life expectancy in the United States increased by 2.3 years from 2000 to 2019, but varied significantly among racial and ethnic groups, according to a new study funded by the U.S. National Institutes of Health (NIH).

The study examined trends in life expectancy at the county level in the United States.

In most counties, life expectancy for the Black population has increased more than any other racial and ethnic group. But overall, the Black population still has a lower life expectancy than the white population, according to the study.

The study noted that the decrease in the white-Black life expectancy gap could be attributed to the stagnation and reversal of gains in the white population.

In addition, American Indian and Alaska Native populations have the lowest life expectancy of all populations and experienced a decrease in most counties, with a gap of more than 21 years in some counties, according to the study.

"The novel details in this study provide us the opportunity to evaluate the impact of social and structural determinants on health outcomes in unprecedented ways," said Eliseo J. Perez-Stable, co-author and director of the National Institute on Minority Health and Health Disparities, part of NIH.

"This in turn allows us to better identify responsive and enduring interventions for local communities," he noted.