Nice review of Claudia Goldin and Lawrence F. Katz’s The Race between Education and Technology which goes into my ever-expanding pile of books to get. Main point: Income inequality decreased in the first half of the 1900s, then, after 1980, increased again. In chapter 8, available in PDF format, is the following conclusion:

Our central conclusion is that when it comes to changes in the wage structure and returns to skill, supply changes are critical, and education changes are by far the most important on the supply side. The fact was true in the early years of our period when the high school movement made Americans educated workers and in the post-World War II decades when high school graduates became college graduates. But the same is also true today when the slowdown in education at various levels is robbing America of the ability to grow strong together.