Ezra Klein continues his fine reporting on the economic effects of education here. He's borrowed the following charts from Catherine Rampell at NYT. Some majors are less disastrous than others, but overall only 55.6% of grads under age 25 have jobs that require college degrees, and 22% are working in jobs that do not. (I don't know whether the other 22.4% includes graduate students or if they are all unemployed.)
College graduates in jobs for which they are overqualified in many cases have displaced qualified high school grads, whose unemployment rates are also soaring. Further, having many more college graduates than there are degree-requiring jobs bids down the wages for those jobs.
A policy response is complicated. Obviously, at a national level we are wasting money to train up millions of young Americans who will get no substantial opportunity to use those skills. However, at an individual level the college credential--as distinguished from the skills--may help win the jobs competition with high school graduates. So, facilitating higher education for disadvantaged youth can be justified as giving them a better opportunity for even mediocre jobs.