Higher education gets you further than it used to. The income payoff of a college degree or above is much larger than just 30 years ago. The reverse is also true: earnings have plummeted for high school dropouts. 

As with the education premium, so with inequality. They have risen together.

Check it out:

Source: https://edsource.org/2014/higher-college-attainment-will-raise-wages-but-not-narrow-income-gap/63535  

But education level is only part of the picture. More important is literacy - understanding, evaluating, inferring from, and using written information.  If you've got high literacy, you've got options. You have a real shot at getting a four-year degree. Even without a four-year degree, you can probably get that foot in the door and work your way up (although I still recommend the degree, which opens more doors and eases the ascension).

The other side of the picture is that low literacy can sink the pretty-well educated. Got a nice technical certificate? Great - but if you have trouble reading, processing information, and problem-solving - all connected with literacy level - moving up the career ladder may be a struggle.

Half of Americans read at an 8th grade level or less.  And so we have a bifurcated society.

References:

Clear Language Group: Readability. http://www.clearlanguagegroup.com/readability/ Accessed 3/29/2017

Higher college attainment will raise wages but not narrow income gap  by Marisol Cuellar and Hans Johnson. EdSource, April 23, 2014