This article is from the archive of our partner National Journal

Americans now owe nearly $1.2 trillion in student loans. The level of debt continues to rise even though the number of active borrowers has gone down since 2010. And even though millennials are the poster generation for student debt, they don't actually hold most of it.

Economists at the Federal Reserve Bank of New York just released some new research based on Equifax credit-report data on repayment rates of student loans. Here are a few things they found:

1. Most people aren't paying off their student loans.

At the end of 2014, only 37 percent of all 43.3 million borrowers nationwide were making payments on time and reducing their loan balances.

About one-third of borrowers had growing debt, likely because they were taking out more loans to pay for more education. Some borrowers were enrolled in programs that allowed them to defer repaying their loans, and 17 percent of borrowers had fallen behind on their payments.

2. This isn't just a young person's problem.

Two-thirds of the nation's student-loan debt is held by people over age 30. The economists found that 30- and 40-somethings have the highest loan balances of all borrowers—an average of about $31,000, compared with the overall average of $26,000.

And when the economists studied groups of students who started repaying their loans in 2005, 2007, and 2009, they found that in all three cohorts, 30-somethings experienced the highest rates of delinquency and default.

3. Student-loan debt is increasingly an problem for senior citizens.

People over age 60 now hold about $43 billion in student loans, and that total is rising fast. Over the past decade, the amount of debt held by seniors shot up 850 percent. A Government Accountability Office report—which I wrote about last year—found that most of the debt held by the elderly was for student loans that financed their own educations. 

4. Making payments is easier if you're rich.

People from low-income areas have much more trouble paying off their loans than people who hail from high-income areas. The Fed's economists didn't know how well-off the borrowers in their data set were, so they looked at a proxy: the average income earned by residents of the zip code that borrowers lived in when they took out their first loans.

The economists found particularly stark differences for the group that entered repayment in 2009, during the depths of the Great Recession. In the aggregate, borrowers from neighborhoods where incomes average less than $40,000 a year have paid down just 3 percent of their debt. Nearly 60 percent have either fallen behind on payments or defaulted on their loans.

Meanwhile, people from neighborhoods where incomes average $80,000 or more have paid off nearly 30 percent of their total debt. Only 20 percent of those borrowers have had trouble making payments.

5. Borrowed a lot of money? That doesn't mean you're likely to default.

In a previous study, economists at the bank found that borrowers from the 2009 cohort who held the smallest amounts of debt—between $1,000 and $5,000—were actually the most likely to default on their loans.

People who started repaying $100,000 or more in loans in 2009 were the least likely to default—but they were also highly likely to enter 2014 with additional debt. To the economists, that suggests that many of those people are either deferring payments or making payments so small that they're not even covering the interest on their debt.

Next America's Education coverage is made possible in part by a grant from the New Venture Fund.

This article is from the archive of our partner National Journal.