More people live to be 100 in the U.S. than in any other country, but it depends on where you live in America.

Since 1960, the life expectancy for men increased by more than 7 years to 74; women are up 6 years to nearly 80.

However, not everyone is living longer.

A Harvard study found life expectancy in areas like the Deep South and parts of the Midwest, like Missouri and Arkansas, is staying the same or even getting shorter.

Researchers think it's an indicator of things to come.

"Something about the public health system is not functioning as well as it should be and it may well just be a matter of time before larger parts of the population are affected," a Harvard researcher said.

Doctors believe increases in cancer, diabetes, and heart and lung diseases in the South and Midwest added to the shorter life expectancies.