Demographic Changes Affecting Family Structure
Longevity increased dramatically in the United States over the twentieth century. The average years lived by a person increased from forty-seven in 1900 to seventy-seven in 2000, and the proportion of persons surviving from birth to old age (sixty-five) increased from 39 percent to 86 percent during the twentieth century. This remarkable change in mortality conditions changed the potential for older people to be involved in family relationships, as the following examples illustrate. (1) A growing number of persons have grandparents living when they reach adulthood. The likelihood of a thirty year old having a living grandparent increased from about 20 percent in 1900 to 75 percent in 2000. Thus the potential for being part of a four-generation family has greatly increased over time. (2) More people now have a parent living through their middle years of life. In 1900 only about 8 percent of sixty year olds had a parent still alive, compared to 44 percent of sixty year olds in 2000. This change has greatly increased the probability that parents and children will have a relationship that extends for sixty or more years. It also has increased the likelihood that a woman approaching old age will be called upon to care for a very old parent. (3) The potential for a husband and wife to cosurvive in a first marriage for more than sixty years has increased significantly. However, because of increasing divorce the actual proportion of older people living with their first spouse for this long has not changed much. (4) The odds of older people having a sibling still alive have increased sharply over time. The cosurvival of siblings may be significant because sibling relationships are frequently valued highly by people in their later years of life.
Declining fertility in the United States over the twentieth century also has affected family relationships involving older people. Women who completed their childbearing around 1900 had an average of about five children each, compared to an average of about two for women completing childbearing around 2000. The trend in childbearing was not smooth over the century, however, because of the baby boom from the mid-1940s through the early 1960s. In the mid 1950s women were averaging about 3.5 children each. Because of fluctuating fertility, the proportion of people in later life who have several surviving children varies over time. As baby boomers (who had low fertility and high rates of childlessness) replace the parents of the baby boom as the older population after 2010, the proportion of older people with no or only one child will increase rapidly. This is potentially significant because children have been an important source of social support and caregiving for older people. Declining fertility also means that those who survive to old age now tend to have fewer children and grandchildren than old people in the past. It has been noted that under high mortality conditions grandparents tend to be in short supply, while under low fertility conditions grandchildren are in short supply.