"You're not getting older, you're getting better," or so promised the famous 1970's ad -- for women's hair dye. Americans have always had a complicated relationship with aging: embrace it, deny it, defer it -- and women have been on the front lines of the battle, willingly or not.

In her lively social history of American women and aging, acclaimed New York Times columnist Gail Collins illustrates the ways in which age is an arbitrary concept that has swung back and forth over the centuries. From Plymouth Rock (when a woman was considered marriageable if "civil and under fifty years of age"), to a few generations later, when they were quietly retired to elderdom once they had passed the optimum age for reproduction, to recent decades when freedom from striving in the workplace and caretaking at home is often celebrated, to the first female nominee for president, American attitudes towards age have been a moving target. Gail Collins gives women reason to expect the best of their golden years.