In the past forty years, the new wave of immigration from Asia and Latin America has begun to rival, in size and scope, the last "great migration" from Europe to the United States at the outset of the twentieth century. As the children of post-1965 immigrants come of age, some observers have started to wonder whether they will meld into American society as their immigrant predecessors did in the early twentieth century or eschew assimilation in favor of a bi-cultural or hybrid identity.

The two decades following World War II were a time of mass upward mobility and declining inequality in the United States, powered by strong business productivity and improved bargaining leverage for workers. The contrast with more recent history is striking. In the quarter century between 1980 and 2005, non-farm business productivity increased 67.4 percent, while the median weekly earnings of full-time workers increased by only 14 percent. And after 1980, as much as 80 percent of the gains in labor income went to the top 1 percent of workers.