Not sure. Probably when the cost of university tuition and boarding started going up.
the problem here is banks being too lenient with loans and credit, especially private unregulated ones.
In Old America, as Jiro calls it, there were much stricter requirements to get approval for a loan.
I looked it up. (I'm such a nerd.

)
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The idea of financial aid started in 1935
While all this was going on,
the actual idea of financial aid for students had been introduced in Indiana in 1935. The Indiana General Assembly legislated mandatory fee remission awards to students on the basis of competitive testing. Subsequently, the Indiana State Financial Aid Association (ISFAA), the first state financial aid association, was formed. In the early 1940s, the Financial Aid Office was created by Indiana University, functioning independently from Student Services, who had taken care of such matters up to that time. The ISFAA was run well, which encouraged other colleges, both private and public, to join the Association.
Through the years, the ISFAA underwent changes in their makeup, moving from a constitution-based organization to one of by-laws. From 1957-1960, when they finally settled on a solid foundation, they assisted the government in creating programs and training opportunities. You see, financial aid was a rather involved business, so the Association needed the training programs to teach each other ways of offering financial assistance. They developed and hosted a program that became very successful over the years.
The U.S. government looked for ways to educate their young
From the outset of the baby boomer age, the U.S. federal government was trying to increase the number of Americans entering college. They were constantly looking for programs that would allow more and more students to go to college. The result of these efforts was a number of programs made available to students from low- to middle-income families.
One of the first acts the government passed after WW II, was the National Defense Education Act, which was designed to revitalize public and private education. This was the act that was specifically introduced as the result of the launching of Sputnik, driven by the government’s desire to be #1. This program is still in effect today, but the name’s been changed to the Federal Perkins Loan program. The program offers low-interest (5%) student loans with up to 10 years to repay, with preference being given to low-income students.
A number of programs were introduced over the next few years, all with the purpose of making it easier for the “common joe” to get a student loan and a higher education. A few of those programs are:
The Health Education Assistance Act,
1963, which offered loans to medical and health program students.
The College Work-Study Program,
1964 (now called the Federal Work-Study Program). In this program, the federal government pays for most of students’ earnings so, in effect it covers their educational expenses.
The Educational Opportunity Grant Program,
1965, which was created specifically for low-income students who couldn’t afford college. No repayment was required.
The Guaranteed Student Loan (GSL) Program,
1965, which is also still in effect today. It’s name was changed in 1988 to the Federal Stafford Loan Program. This program provided more money for student loans through banks or lending agencies, to offset rising education costs.
The Middle Assistance Act,
1978, provided student loans to middle-class families. This act, in effect, removed the income limit on federal aid programs.
The Parent Loans for Undergraduate Students Program,
1981, allowed upper-income families to get student loans, but at much higher interest rates.
You can see that the pattern of these programs followed a definite path – they went from emphasis on campus-administered aid programs in 1965, to a basic grant approach in 1972, to an inclusion of lower income as well as middle income families in 1978. The evolution of student loans was very diverse and constantly changing."
The History of Student Loans