The Causal Impact of Education on Economic Growth: Evidence from U.S. Philippe Aghion, March 2009, Paper. "Should countries or regions (generically, "states") invest more in education to promote economic growth? Policy makers often assert that if their state spends more on educating its population, incomes will grow sufficiently to more than recover the investment. Economists and others have proposed many channels through which education may affect growth--not merely the private returns to individuals' greater human capital but also a variety of externalities..." Link