How predatory lenders and private interests gave student loans a bad name.

When the president proposed his education budget this week, there was a lot for both the poor and the upper-middle class to like. For low-income students, the budget includes a substantial increase in Pell grants (government money for college). For the upper-middle class, it's even better, with a $2,500-a-year tax credit for students or parents paying for college.

One thing, however, was conspicuously missing from the education plan: an increase in the amount of money students can borrow via federally subsidized loans.

Now, maybe students aren’t in the mood to borrow more—aren’t college graduates already terrifically overburdened with enormous loan payments? That's certainly what you might think from the public discussion of excessive corporate profits and crushing student debt. The reality, though, of the federal loan program is more complicated. It's not the story of failure that many folks would imagine. It's a story of how neglect and the interests of private lenders—and to some extent, those of a small group of for-profit schools that have abused the system—have smothered one of the government's most successful programs.

Stories about the travails of students who find themselves hopelessly in debt obscure a truly stunning fact: The amount that students can borrow in federally subsidized loans has remained almost unchanged for more than 15 years.

In 1993, the total that an undergraduate could borrow over four years in federally subsidized loans from the Stafford loan program was $17, 125. Since then it has risen to $19,000—a total of about 11 percent. Often in stories about college costs, you see numbers “adjusted for inflation.” So just to get this clear: Right now, most undergrads can borrow all of $1,875 more in subsidized loans over their four years of college. Period.

How much has the cost of college gone up since then? In the 1993-1994 academic year, according to the College Board, the average tuition at a four-year private college at the time was $11,007. It is now $26,273. Four-year public colleges? Same story: up from $2,535 to $7,020.  You can do the precise math yourself, but here's the bottom line: The money that students have available from subsidized loans has stayed almost constant, while the cost of college has risen more than 150 percent.