Wages for more- and less-educated workers have followed strikingly different paths in the U.S. and Canada. During the 1980's and 1990's, the ratio of earnings of university graduates to high school graduates increased sharply in the U.S. but fell slightly in Canada. Katz and Murphy (1992) found...

Our model of growth departs from both the Malthusian and neoclassical approaches by including investments in human capital. We assume, crucially, that rates of return on human capital investments rise, rather than, decline, as the stock of human capital increases, until the stock becomes large....