Many factors contribute to growing student debt. One that's mentioned less frequently than others is the time it takes to complete a degree — and it can significantly impact the amount a student ends up owing.
In 1989 it cost about $17,010 a year to attend a private four-year college and $3,360 a year to attend a public four-year college, according to the College Board. Today, those prices are closer to $35,830 and $10,230, respectively.
According to the National Center for Education Statistics, just 41% of first-time full-time college students earn a bachelor's degree in four years, and only 59% earn a bachelor's in six years, driving up the cost of attending college significantly. Many of these students are left with the debt of a college education without the degree.
Though scholarships and grants have helped to keep net prices from rising as dramatically as they might otherwise, today, roughly 44 million Americans collectively owe $1.56 trillion in student loans.
Even one of the U.S.'s most famous college dropouts, Bill Gates, says low graduation rates are a crisis that needs to be addressed. "Without more graduates," Gates wrote on his blog, "our country will face a shortage of skilled workers and fewer low-income families will get the opportunity to lift themselves out of poverty."
Experts point to several reasons why four-year college graduation rates in the U.S. are so low.
Nicole Smith, Chief Economist at the Georgetown University Center on Education and the Workforce, tells CNBC Make It that unequal elementary, middle and high schools for low-income Americans leads to issues of preparedness that set these students up to struggle.
Students who come to college under-prepared may find themselves overwhelmed by the rigor of college and drop out if they can't find adequate support from their school.
"We still have a lot of locations in this country that are 'AP deserts,' that don't have calculus in an entry-level, or college-level courses even on the curriculum at these high schools, depending on the location," says Smith. "It's almost a foregone conclusion that students who graduate from these high schools, or who leave these high schools, are not going to go to college. And if they do, [they] are going to have a much harder time completing the course load."
Unexpected financial and personal challenges frequently get in the way of students' plans. "Life," Smith says, "just happens."
This is particularly true for the many Americans who are going to college later in life. In 2018, there were 12.3 million college and university students under the age of 25, and 7.6 million students who were 25 years old and over. For these older students, family and work responsibilities can make graduating on time a challenge.
Financial barriers can force students to take time away from their studies. Sara Goldrick-Rab, professor at Temple University, author of "Paying the Price " and founder of the Hope Center, tells CNBC Make It that basic needs, including hunger and homelessness, are factors that contribute to low college graduation rates.
"There's no question that [insecurity] is a part of the dropout rate problem," says Goldrick-Rab. "We can see very strong relationships between these issues and the chance that a student will get good grades so they keep their financial aid, to make it to the next semester, to make it to graduation."
At some large universities students struggle to enroll in the classes they need to take in order to graduate on time.
The ability to accommodate student needs is one reason that graduation rates are significantly higher at elite schools. All of the six schools ranked highest by U.S. News & World Report had graduation rates above 97%.
One of the easiest ways to keep your cost of attending college down is to avoid the common financial traps college students often fall into. If possible, avoid keeping a car on campus. Choose your housing wisely, and do your research before opening a credit card.
But one of the best ways students can avoid spending unnecessarily is by planning their path to graduation as soon as possible. Map out what classes you will need to take in order to earn your diploma on time, make an appointment with your dean and find a professor who is willing to guide you. Make the most of on-campus resources, and if you need help — ask for it.
Ultimately, staying on track can save students from spending additional thousands of extra dollars on college.
Like this story? Subscribe to CNBC Make It on YouTube!