It is a modern American truism: College is too expensive. Four years of Harvard College tuition costs roughly triple the median American’s 2010 net worth. And yet, according to the federal government’s newly unveiled “College Scorecard,” a Harvard education is comfortably cheap. That conclusion stems from a net-cost analysis (tuition minus grants and scholarships) for students receiving financial aid: an average tally of $18,277. Unfortunately, while that calculation anoints Harvard as the Ivy League’s cheapest school, this case proves one in which popular knowledge (that college is too expensive) outdoes the raw numbers’ suggestion. Harvard’s net cost is one bright but flickering spot, cast against a grimmer backdrop of painful college expenses, a challenge that the federal government should address.

Before launching into that discussion, the accomplishment behind the $18,277 number deserves some plaudits. A genuine round of applause for a concerted effort by the College and alumni to make a Harvard education affordable and for a recent trend of decline in average net price—15.5 percent over 2007-2009. A round of applause for keeping student debt at a minimum, $88.61 per month versus other Ivy League figures all in the triple digits. And a round of applause for beating Yale.

But bear in mind that those numbers miss the makeup of the Harvard student body, one of the nation’s richest. U.S. News places Harvard sixth among its Top 25 Universities in Pell Grant percentage, a useful proxy for economic diversity. Yet that ranking says little about a school in non-relative terms. Zooming in on Harvard, per the Admissions Office’s factsheet, 20 percent of students’ families have incomes below $65,000, an automatic trigger for full financial aid. That means incomes in Harvard’s bottom quintile span the United States’ bottom three (the third tops out around $62,000), something less than a paragon of equity. Harvard’s Scorecard cost is as much a function of its students’ circumstances as it is of institutional efforts or innate munificence.

Not every American college shares those circumstances. Instead, nationwide growth in college costs have consistently outpaced inflation. The typical American student graduates with nearly $27,000 in student loan debt; the typical Harvard aid package contains no loans, with grants in lieu of them. This is not to gush over Harvard’s progress—it is to show that, nationally, something needs to be done. In particular, the U.S. federal government should prioritize investment in education.

In pared-down economic terms, that investment makes sense. Research here at Harvard has found that in recent years, labor market demand for college graduates has outstripped supply. The historically high college wage premium is a sure call for more graduates, which federal funding can engender. Education investment is a key element for long-term economic growth.

Beyond supply and demand curves, however, education funding can also address inequality and opportunity. Specifically, Harvard economists Claudia Goldin and Lawrence F. Katz, authors of the study above, attribute 60 percent of the growth in wage equality between 1973 and 2005 to increasing returns for education. Investment, of course, is needed long before college (rich-poor achievement gaps originate much earlier), but it should certainly persist throughout. And as an additional sign of potential, research suggests that college’s benefits are strongest for poorer students.

Socioeconomic mobility has long stood as a storied American promise. Today, education, not merely legal protections, is the modern bulwark against ossification. Our government’s budget should better reflect that.