From today's New York Times:
According to new research by Betsey Stevenson and Justin Wolfers of the Wharton School at the University of Pennsylvania, the happiness gap between blacks and whites has fallen by two-thirds since the early 1970s. The gender gap (women used to be happier than men) has disappeared. Most significant, the disparity in happiness within demographic groups has also shrunk: the unhappiest 25 percent of the population has gotten a lot happier. The happiest quarter is less cheerful.
It seems odd that happiness would become more egalitarian over a period in which the share of the nations income sucked in by the richest 1 percent of Americans rose from 7 percent to 17 percent. In fact, the report does find a growing happiness gap between Americans with higher levels of education and those with less, which is roughly in line with the widening pay gap between the skilled and unskilled.
But other things have evidently been going on that are affecting Americans contentment. The big decrease in the inequality of cheer occurred roughly between the early 1970s and 1990 a time of vast social and legal change when new freedoms and protections made their way into different aspects of life and work. Together with new technologies, like the pill, they have given people more control over their lives.