In 1900, an American alive at age 50 could expect to live another 21.3 years to 71.3 years.
In 1950, a 50-year old American could expect to live another 24.4 years to 74.4 years.
In 2003, a 50-year old American can expect to live another 30.6 years to 80.6 years (78.5 years for men and 82.4 years for women).
Good news: We have gained more than 9 years of life expectancy since 1900 for 50-year olds, a 44% increase, and we have gained more than 6 years of life expectancy since 1950, a 25% increase.
Bad news: Social Security is financially insolvent and headed for a meltdown, largely because it was designed in the 1930s, before the significant increase in life expectancy.