According to a recent study, wedding bells are not ringing for the majority of younger adults in the United States, while marriage rates for older adults have increased over the past 50 years.

The study, conducted by the Institute for Family Studies, showed that only 48.6 percent of adults in the U.S. between the ages of 18-64 are currently married – marking an all-time low, according to the most recent census data from IPUMS-USA.

"The short-term fluctuation in the number of new marriages and divorces is closely related to changes in the economy and other factors," stated Wendy Wang, a director of research at IFS.

"In the long run, with the passing of older generations, we are heading to an age when marriage will no longer be the institution that a majority of adults live in," Wang continued.

According to the research, there are a number of different factors playing into this decline. More couples are marrying later, or have decided to live with their significant other instead of getting married. Additionally, the number of never-married adults in this age group rose from 26 percent in 1990 to 36 percent in 2016.

The study also found that individuals who are under the age of 35 and those without a college education are more prone to staying unmarried.

"Marriage remains the norm for those with a college education," Wang noted.

In addition, the decline in marriage for young adults was seen across the board, from varying racial and ethnic groups, and included both men and women.

One positive trend from the decline pointed to a lower divorce rate, which reached a record low of 2.1 million in 2016. For those adults who are married, the chance of divorce is now lower.

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"Although a smaller share of adults is married today, among those who are married, the good news is that their likelihood of divorce is also lower," Wang said.

On the other hand, marriage for adults in their retired years, 65 and older, is seeing a slight increase, rising from 36 percent to 45 percent in 2016.

Factors such as longer life expectancies, particularly among men, were a major contributor in the increase of marriage for older adults. While older men previously outnumbered women among married adults in their age group, the gap has become more narrow in recent years. Today, for every 100 married men above the age of 65, there are 80 married women – compared to 64 women in 1960.

The study also noted that the divorce rate among this age group has roughly remained the same – around 3 new divorces per 1,000 married adults since 2008.

In the future, Wang is predicting that the gap between married and non-married younger adults will most likely continue to grow.

"The gap between married adults and those who are not married, aligning with the class divide in the U.S., is likely to deepen in the near future."