David A. Kindig, a professor emeritus of population health sciences and founder of the Population Health Institute, and Erika R. Cheng, a doctoral candidate, at the School of Medicine and Public Health said U.S. male mortality rates increased in only 3.4 percent of the counties.
U.S. female mortality rates increased in 1,224 counties compared to an increase in 108 counties for men.
The study found for both men and women, factors associated with lower mortality included having a college degree, higher median household income, Hispanic ethnicity and living in a higher population density area.
For women, living in counties in the South and West was associated with a 6 percent higher mortality rate than living in the Northeast.
Smoking rates were a key factor in higher mortality rates, Kindig said.
The findings were published in the journal Health Affairs.