The true history of the U.S. since 1980, IMHO at least, is not Sean Wilentz's "Age of Reagan" but is instead composed of a half dozen or so deeper and broader tides, like:
1. The end of the Cold War
2. Other winner-take-all factors that have, in combination with education, pushed American income polarization back to Gilded Age levels.
3. The failure of American taxpayers to support their state and local governments in expanding funding for public education--and the impact of reduced public education effort in sharpening the distinction between rich and poor.
4. The computer revolution in productivity growth.
5. The rise of China (and soon, we hope, India) as industrial powers.
6. The extraordinary social liberalization of America
Tyler Cowen quarrels with number 3, and I will quarrel even harder. No one who claims to be reality-based would argue that (a) spending on public education has fallen or (b) that spending on public education makes a large difference. Brad DeLong needs to spend some time with James Heckman.
I don't think you can tell the story of the last quarter century without saying something about assortative mating. Also, keep in mind what Kay Hymowitz calls Marriage and Caste, in which affluent people are more likely to have their children within marriage and to remain married, while less-affluent people have out-of-wedlock children and higher divorce rates.