Consideration of additional factors only adds to the puzzle.
First, the fraction of women ages 25 to 64 participating in the labor force and contributing to household money income skyrocketed during this period, increasing from 57 percent to 76 percent between 1970 and 2000 according to data from the Current Population Survey.
At the same time, average levels of education grew substantially.
In 1970, 48 percent of individuals over age 25 had less than a high school education; by 2000 this figure had fallen to 17 percent (U.S. Bureau of the Census, 2004).
Finally, the stickiness in the non elderly poverty rate does not exist for all demographic groups in the United States: poverty rates among the elderly declined steadily during this period, falling from 24.6 percent in 1970 to 10.2 percent in 2003.