Among 50-year-old men, for example, those in the highest education group are now projected to live almost six years longer on average than those in the lowest education group -- and this differential has been rising sharply. The widening gap in life expectancy is also evident geographically. In 2007, men living in the American counties with the greatest average longevity could expect to live more than 15 years longer than men in the lowest- ranked ones. In 1987, that gap was less than 12 years. Sadly, life expectancy in some counties actually declined over that period.
The leading explanations for this involve health behavior -- including diet, exercise and smoking. For example, men 50 and older without a high-school education are more than twice as likely to smoke as those with a college degree. Exercise behavior also varies substantially. Among 45- to 54-year-olds in one study, only 16 percent of those without a high-school degree exercised vigorously at least once a week, whereas 56 percent of college graduates did.