For years those pushing kids to go to college noted that there was a huge and growing earnings differential between high school and college graduates, making college a good investment even with soaring tuition fees. I have argued that the end to that rising income differential, along with higher fees, is now lowering the rate of return on the financial investment of going to college, and markets are starting to respond as manifested in falling enrollments.

But there is another, arguably even better measure of economic well being than income, namely wealth. Forbes does not publish a list of the 400 Americans with the highest incomes, but rather those who have accumulated the most wealth. When people say “Jeff Bezos is the richest man in the world,” they are talking about his wealth, not his annual income. Three researchers at the Federal Reserve Bank of St. Louis (William Emmons, Ana Hernandez Kent and Lowell Ricketts) have gathered estimates of income and wealth by educational attainment and noted that the wealth differential associated with a college degree has declined for more recent graduates. They looked at the income and wealth of college graduates by the decade in which they were born. The patterns on income were somewhat mixed and not necessarily inconsistent with other evidence.

But it is a different story for wealth. Compare the cohorts born in the 1930s, 1950s, 1970s and 1980s. Look at white, non-Hispanic college graduates in each cohort compared with those without degrees. The college wealth advantages for the four decades are, respectively, 247%, 185%, 134%, and 42%. For blacks, the numbers are even more dramatic, with large differentials for cohorts born in the 1960s and earlier almost completely disappearing with the 1970s and 1980s cohorts. Moreover, the advantage of earning advanced degrees is shown to have also declined for both whites and blacks.

It takes time for wealth to accumulate, and people are far wealthier in their seventies than they are in their forties. I am not absolutely sure whether the St. Louis Fed researchers have fully accounted for the impact of aging on wealth accumulation, but it certainly appears that the wealth advantage associated with college attendance is probably in significant decline.

Why? There are several possible explanations, but one very obvious one is that it takes far more resources to obtain a college degree today than it did several generations ago. Today, for example, there is $1.5 trillion in student loan debt outstanding, triple the amount of, say a little more than a decade ago. Higher debt, lower net wealth. To get the income differential associated with a degree, people sacrifice increasing amounts of wealth. The ratio of wealth to income among college graduates appears to be falling over time.

Other factors could be at work as well. For example, the cohort born in the 1930s attended college mostly in the 1950s, when far less than- 10 percent of adult Americans had college degrees, while their counterparts of a half century later attended universities mostly in the first decade of this century, when over 25 percent of adults were college graduates. Those born in the 1930s were considered somewhat elite—they were part of a small minority of presumably unusually bright, motivated, and disciplined persons—often from fairly wealthy families. That was probably distinctly less so 50 years later.

The dramatic decline—nearly disappearance—of the collegiate wealth advantage for blacks needs an explanation. African-Americans generally have lower incomes and wealth than whites, so the burden of attending college is greater on them—student debt is particularly high for blacks relative to either income or wealth. The data seem to suggest that the push to increase minority representation in colleges possibly is somewhat misplaced from a purely economic perspective. Why are we encouraging minorities to go to college and even in some cases giving them preferential admissions if there is little or no wealth advantage associated with a college degree? The same is true to a lesser extent for others as well .

Much of the best work on financing college is done by researchers at Federal Reserve Banks. I probably will irritate some colleagues, but university researchers of this topic have a potential bias and even conflict of interest, as their own income and wealth is enhanced by stories of prosperity relating to college graduates.