1984: Because the Census Bureau is not yet capturing data on cohabitation, estimates are required to reflect the trend of people living together without being married. This estimate was given the acronym POSSLQ, “Persons of the Opposite Sex Sharing Living Quarters.” In 1984, the estimated number of POSSLQs was 2.4 million.

Today: According to the U.S. Census Bureau, as of the year 2000, more than 11 million unmarried people live with a partner. This represents an increase of 72 percent since 1990 and is ten times the number of people who were cohabitating in 1960. The Centers for Disease Control and Prevention announces in 2002 that 41 percent of women between the ages of fifteen and forty-four have lived with someone at some point in their lives.

1984: The median age for a woman's first marriage is twenty-two, more than a year older than a decade earlier. According to the U.S. Census Bureau...