2.2. HOW LIFE EXPECTANCY HAS CHANGED

Around 1900, average life expectancy at birth in the United States was just over 49 years. Because of healthier foods and lifestyles and medical advances, it has kept increasing. Measured every 10 years (based on the 10-year censuses that we have), it finally passed age 70 in 1970, hitting 70.8 years. Based on the 2000 census, it reached 76.9 years in 2000. The progression of life expectancy at birth throughout the twentieth century is illustrated in Figure 2.1.

Much of the improvement came about because deaths at younger ages started to decline. Thus, for the average survivor to age 65 (a relatively small group in 1900), the future life expectancy was then 11.9 years. That increased to 15.0 years by 1970. That means that, of the total increase in life expectancy at birth (from 49.2 years to 70.8 years, an increase of 21.6 years), only a small portion came from higher survival rates after reaching age 65; the other 18.5 years of the improvement between 1900 and 1970 came from fewer people dying at ages below 65, because they didn't die in their infancy or their youth.

Figure 2.1. Life Expectancy at Birth, 1900–2000

In 2000 the average life expectancy at age 65 reached 17.9 years. The increase since 1970 in the average expectancy at birth is 6.1 years (from 70.8 to 76.9), while the increase in expectancy after age 65 is 2.9 years (from 15.0 to 17.9), so the effect of survival rates after age 65 has been proportionately much bigger in recent years. This is because there is now much less scope for increasing longevity between birth and age 65; most of the improvement has already taken place. In the future, most of the improvement in life expectancy at birth is likely to take place after age 65, as medical science continues to improve our chances of survival when disease hits us in old age. Figure 2.2 illustrates the increase in life expectancy at age 65 over the past century.

Of all Americans born, the proportion reaching age 65 as of the 2000 census was just above 82 percent (about 78 percent for men and 86 percent for women). Figure 2.3 shows the percentage of Americans reaching age 65 from 1900 to 2000.