We study biological aging of elderly U.S. Americans born 1904-1966. We use thirteen waves of the Health and Retirement Study and construct a health deficit index as the number of health deficits present in a person measured relative to the number of potential deficits. We find that, on average, Americans develop 5 percent more health deficits per year, that men age slightly faster than women, and that, at any age above 50, Caucasians display significantly less health deficits than African Americans. We also document a steady time trend of health improvements. For each year of later birth, health deficits decline on average by about 1 percent. This health trend is about the same across regions and for men and women, but significantly lower for African Americans compared to Caucasians. In non-linear regressions, we find that regional differences in aging follow a particular regularity, akin to the compensation effect of mortality. Health deficits converge for men and women and across American regions and suggest a life span of the American population of about 97 years.