We talk about it all the time in workforce development, and MDRC has quantified it this terrific chart, using 2006 Census data. Getting that high school diploma gets you $10 grand a year more than dropping out, a two year degree gets you $8,000 more, and that college degree another $16K (nearly double what you'll earn with a H.S. diploma). Click here to see more MDRC Fast Facts.
This is the answer to the question we get from participants, "Why should I keep going to school?" It's also the answer to the political question, "Why should we reduce work requirements and extend TANF [and other benefits] to allow program participants to stay in school longer?"