This week Americans celebrate National Marriage Week, a collaborative campaign to strengthen individual marriages, reduce the divorce rate, and build a stronger marriage culture. Here are five facts you should know about marriage in America:

1. Most Americans don’t marry young

Remember when most Americans got married when they were still teenagers? You probably don’t since that hasn’t been true for at least 125 years. Since 1890 the median age for a man’s first marriage was 26.1; the median age for a woman's first marriage was 23.7. The lowest median age for both men and women occurred from 1950 to 1960. During that period the median for men was 22.8 and 20.5 for women.

Today, though, Americans are getting married later than ever before: In 2010, the median age for men was 28.2 years and 26.1 years for women. The following table shows the median age of American men and women when they were first married from 1890 to 2010.

2. More Americans are cohabitating before marriage

Prior to the 1960s, unmarried cohabitation — the status of couples who are sexual partners, not married to each other, and sharing a household — was rare in America. In 1960, there were around 439,000 Americans cohabitating. Today, that number has increased sixteen-fold to around 7.6 million.

Most younger Americans now spend some time living together outside of marriage, and unmarried cohabitation commonly precedes marriage. It is estimated that about a quarter of unmarried women age 25 to 39 are currently living with a partner and an additional quarter have lived with a partner at some time in the past. More than 60 percent of first marriages are now preceded by living together, compared to virtually none 50 years ago.

3. Unmarried with children

While many Americans cohabitate before getting married, for many couples, cohabitation has replaced marriage. Cohabitation is particularly common among those of lower educational and income levels. A 2010 report found that among women in the 25 to 44-age range, 75 percent of high school dropouts have cohabited (compared to 50 percent of college graduates). Cohabitation is also more common among those who are less religious than their peers, those who have been divorced, and those who have experienced parental divorce, fatherlessness, or high levels of marital discord during childhood.

A growing percentage of cohabiting couple households — now over 40 percent —also have children. Currently, 48 percent of all first births are now to unmarried women. Despite the common perception of unwed mothers being teens, most are in their twenties. Sixty percent of unwed births are to women in their twenties while only 23 percent are to teenagers.

4. It’s true that the divorce rate is almost 50 percent – but it doesn’t mean what you might think.

The national divorce rate is almost 50 percent of all marriages. But for many people, the actual chances of divorce are far below 50/50. For first marriages recently formed, between 40 and 50 percent are likely to end in divorce. The divorce rate for remarriages is even higher.

But the "close to 50 percent" divorce rate refers to the percentage of marriages entered into during a particular year that are projected to end in divorce or separation before one spouse dies. Such projections assume that the divorce and death rates occurring that year will continue indefinitely into the future — an assumption that is useful more as an indicator of the instability of marriages in the recent past than as a predictor of future events. So while the divorce rate is 50 percent, it doesn’t mean the probability of every married couple getting divorced is 50 percent.

5.  Not all marriages are created equal

There are a number of factors that are correlated with a strong marriage. For instance, teenagers and the nonreligious who marry have higher divorce rates than those who marry later and are religious. In fact, if a person has been to college, has an annual income over $50,000, is religious, comes from an intact family, and marries after age 25 without having a baby first, their chances of divorce are very low.