The study suggests the rising rate stems from a snowball effect. As the baby boom generation greys, it represents the “first cohort to divorce and remarry in large numbers during young adulthood.” Married people who have previously been divorced are 2.5 times more likely to divorce again, so as baby boomers enter their second or third marriages, the risk of divorce rises at an ever increasing rate.

Young and middle-aged couples are traditionally responsible for America’s high divorce rate, but a new study reveals that couples over the age of 50 are catching up.

About 45 percent of marriages in the United States end in divorce, and now 1 in 4 of those are by couples over 50, according to the Bowling Green State University study. Even as the divorce rate growth flattened out overall, the divorce rate among older adults doubled between 1990 and 2009.

The study suggests the rising rate stems from a snowball effect. As the baby boom generation greys, it represents the “first cohort to divorce and remarry in large numbers during young adulthood.” Married people who have previously been divorced are 2.5 times more likely to divorce again, so as baby boomers enter their second or third marriages, the risk of divorce rises at an ever increasing rate.

The study’s authors said as more people get divorced, the practice becomes socially accepted, and divorce rates rise even faster.

Other strong factors for the risk of divorce: Marriage length, employment, race, and education. Older couples married less than 10 years are 10 times more likely to get a divorce than those married 40 years or more. Unemployed couples divorce most often. Higher education means a lower risk of divorce, and African-Americans and Hispanics have a higher risk than whites and Asians.

But these statistics only describe trends, rather than dictating outcomes. One couple in WORLD’s marriage longevity series, Sam and Mary Ester Council, would be considered likely candidates for divorce: They conceived their first child before getting married at 17, and spent their first few years together with their parents. But the couple have now been married for 42 years.

June and Bert Wells also refused to become statistics: Bert, a widower, and June, a 34-year-old divorcée, started a second marriage together in 1972. Determined to work on their marrige and not give up, they remain married today.