If you married before 1950, the chances are your marriage lasted at least 15 years, probably 25 and likely even longer. If you married after 1980, however, your prospects are not as rosy. In fact, you are less likely than at any time since World War II to celebrate a Silver wedding anniversary — 25 years of marriage.

In other words, Americans are not taking the marriage vow of lifelong fidelity to heart these days. Thus, while the divorce rate remains fairly constant at about one in five, those married since 1980 are more likely to divorce.

This new information, the latest from the Census Bureau, reveals that about 70 percent of couples who married in the 1950s remained married long enough to celebrate their 25th wedding anniversary. In contrast, less than half of the couples married in the late 1970s were still married 25 years later (49.5 percent of men and 46.4 percent of women).

While vows of fidelity are not taken as seriously, they are also not taken as soon. More couples are marrying later in life. In 1996, nearly half (49 percent) of men in their late 20s had never married, and over one-third (35 percent) of twenty-something women had never married. By 2004, among people in their late 20s, over half of the men (54 percent) and more than 40 percent of the women (41 percent) were classified as "never married."

Couples today don't go straight to marriage. More couples are living together before getting married. In addition to the dramatic increase in the number of never-married twenty-somethings, the Census Bureau reports that the number of unmarried partner households rose from 5 million to 6 million between 2000 and 2006. About 70 percent of couples getting married have lived together before their marriage. Ironically, the couples are often motivated to live together to "see if they are compatible," yet studies show that living together before marriage is more a recipe for divorce than a way to determine whether a marriage will be successful. Couples who live together before marriage are 80 percent more likely to divorce than are couples who don't.

These destructive trends are interlocked; they represent dramatic changes in the character of the institution of marriage. An earlier Census Bureau report noted a sea change in marriage: slightly over half (50.2 percent) of American households were composed of unmarried people (single heads of households and non-family groups) with traditional married couples constituting slightly less than half of households (49.8 percent). Among individuals, the rate increased one-third between 1960 and 2006 (from 32.4 percent in 1996 to 45.2 percent in 2006).

All this happened in a very short time frame. Just six years ago, married couples made up 52 percent of American households, and between 2000 and 2006, the number of unmarried women grew at twice the rate as married women. More American women than ever before in history are living without a husband — over half (51.2 percent) are divorced, separated, widowed or never married. According to a report, Unmarried America, 2007, unmarried Americans are less involved with their communities, less likely to belong to a group or a church, and have fewer ties with their neighbors. They are more influenced by media (television and movies) and they are less likely to watch television news or to read newspapers.

These changes are profoundly reshaping American society. These changes in family structure are indeed a qualitative weakening of critical magnitude, being especially detrimental to the well being of women and children, who bear the brunt of such cultural trends. If current conditions continue, 40 percent of all American children will spend some time in their childhood living in the household of a cohabiting couple — where they are at risk of a wide range of negative outcomes as documented by the Urban Institute and other research institutions.

Yet, ancient Rome's great orator and statesman, Cicero, declared that marriage was the "first bond of society." Indeed, throughout history, marriage has been at once both the cornerstone and keystone of civilized societies, while sexual promiscuity has been a corrosive, destructive force weakening a civilization. Reo Christenson studied more than eighty early societies and found a strong correlation between sexual restraint and social progress. "Cultures that were more sexually permissive," he found, "displayed less cultural energy, creativity, intellectual development and individualism, and a slower general cultural ascent."

Indeed, the weight of evidence is overwhelming: the traditional family with a married mother and father committed to each other for life not only forms the best environment for children, it is essential to the effective functioning of the entire community. Thus, lifelong marriage provides an unequaled foundation for a strong and vibrant nation.