Over the past century, families in the United States and most of Europe have undergone sweeping changes across all social and demographic groups. The age at marriage rose, nonmarital cohabitation became common, and divorce rates skyrocketed. Some demographers refer to these broad changes in family life as the Second Demographic Transition. (The original Demographic Transition was the shift from high birth and death rates to low birth and death rates experienced first by Western Europe and eventually by all countries). Because these changes have occurred in both good economic times and bad, and have affected all socioeconomic groups, many believe that changing ideas about the family have helped drive them.57
