A fascinating fact: "An average person born in the United States in the second half of the 19th century completed 7 years of schooling and spent 58 hours a week working in the market. In contrast, an average person born at the end of the 20th century completed 14 years of schooling and spent 40 hours a week working. In the span of 100 years, completed years of schooling doubled and working hours decreased by 30%."
Restuccia, Diego and Vandenbroucke, Guillaume ask "What explains these trends?"
Their paper (link below) quantitatively assessed "the contribution of exogenous variations in productivity (wage) and life expectancy in accounting for the secular trends in educational attainment and hours of work."
And the result? "We find that the observed increase in wages and life expectancy accounts for 80% of the increase in years of schooling and 88% of the reduction in hours of work. Rising wages alone account for 75% of the increase in schooling and almost all the decrease in hours in the model, whereas rising life expectancy alone accounts for 25% of the increase in schooling and almost none of the decrease in hours of work."
Restuccia, Diego and Vandenbroucke, Guillaume, A Century of Human Capital and Hours (July 2013). Economic Inquiry, Vol. 51, Issue 3, pp. 1849-1866, 2013. http://ssrn.com/abstract=2261571
Aside 1: note that higher wages (when aligned with higher productivity) imply higher human capital intensity and lower hours of wrok supplied.
Aside 2: there seem to be no control for the reporting of hours supplied. In mid-19th century and even in first half of 20th century, most of work performed was time-sheeted. Today, majority of us do not have time cards, so on the surface, our contracts say 40 hours per week, in reality this means 60 hours per week.