Median US Income By Education Level

From Tax Foundation, "Median Incomes Vary Greatly by Educational Attainment" by Scott A Hodge and Andrew Lundeen:

One of the biggest contributors to rising inequality in America today is the growing earnings gulf between workers with college degrees and those without. Indeed, the median income for all households was $51,244 in 2011. By contrast, the median income for a household headed by a worker with a four-year college degree was $78,251, more than 50 percent above the typical household. Those with professional degrees earn more than twice the median household income.

Source: Tax Foundation