Fewer women are getting married and they're waiting longer to tie the knot when they do decide to walk down the aisle. That's according to a new Family Profile from the National Center for Family and Marriage Research (NCFMR) at Bowling Green State University.

According to "Marriage: More than a Century of Change," the U.S. marriage rate is 31.1, the lowest it's been in over a century. That equals roughly 31 marriages per 1,000 married women. Compare that to 1920, when the marriage rate was a staggering 92.3.

Since 1970, the marriage rate has declined by almost 60 percent. "Marriage is no longer compulsory," said Dr. Susan Brown, co-director of the NCFMR. "It's just one of an array of options. Increasingly, many couples choose to cohabit and still others prefer to remain single."

Furthermore, a woman's average age at first marriage is the highest it's been in over a century, at nearly 27 years old. "The age at first marriage for women and men is at a historic highpoint and has been increasing at a steady pace," states Dr. Wendy Manning, co-director of the Center.

There has also been a dramatic increase in the proportion of women who are separated or divorced. In 1920, less than 1 percent of women held that distinction. Today, that number is 15 percent. "The divorce rate remains high in the U.S., and individuals today are less likely to remarry than they were in the past," reports Brown.

The marriage rate has declined for all racial and ethnic groups, but the greatest decline is among African Americans. Similarly, the education divide in marriage has grown. In the last 50 years there have been only modest changes in the percentage of women married among the college educated and the greatest declines among women without a high school diploma.

Researchers used data from the National Vital Statistics "100 Years of Marriage and Divorce Statistics United States 1867-1967," the Centers for Disease Control and Prevention/National Center for Health Statistics, and the U.S. Census Bureau.