You appear to be using the value from the "Persons, age 25+, employed full-time" row and "Bachelor's degree or higher" column? If so, that is not the median per-capita income of people in the US. Median per-capita income is, as the person you just replied to quoted:

15 years and older: $28,567

18 years and older: $24,062

25 years and older: $32,140

And note that we should not be using the median of the general population, but instead the median of the population that did not attain a bachelors degree and comparing that to the median of the population that did attain a bachelors, but no higher, degree.

Taking the unweighted average income of those over 25 years of age who have completed some high school, graduated high school, and completed some college and comparing it to those over 25 years of age who have attained a bachelors degree you come up with

($25,039 + $31,539 + $37,135) / 3 = $31,238 Income of those with a bachelors degree $50,944

I only meant to dispute the claim of @wyldfire that a difference of $640,000 (1987 USD) is "really small." Even this comment does not represent a rigorous assessment of the value of a college degree. See The College Payoff: Education, Occupations, Lifetime earnings [0] if you want that assessment.

[0] https://repository.library.georgetown.edu/handle/10822/55930...