Given the seven years that have passed since the last revision of this text, myown thinking has changed about the chronology applied to the demographic historyof the 20th century. It is now evident that the decade of the 1960s for theUnited States, as well as for most of the world, was a profound marker ofchange. The sudden decline in fertility that occurred in the decade of the 1960swas considered at the time to be a temporary phenomenon. But it is now evidentfrom all the advanced industrial societies that this new low-low fertility, asthe demographers are calling this change, is a permanent part of theposttransitional model of demographic change for all advanced industrialsocieties. All the major industrial states are now at or below replacementfertility, and most of the developed world is quickly following their lead. Thesecond factor marking the decade of the 1960s as important was the change inimmigration laws in the United States, which again opened up the country to anew era of international migration in the following decades, which in turn ledto Hispanics emerging as the largest minority in the country. Thus, I haveconfined the postwar chapter to the period 1945–1970 and have used the1970 census as a terminal point, with some suggestions of how changes whichbegan in the late 1960s saw their full development in the 1970s.