The expansion of agricultural lands led to what superficially seems a paradox: the more farmers there were—and the more productive farmers became—the smaller was agriculture's share of the economy. Farmers had the largest share of the dollar value of American economic output until 1880, when commerce's 29 percent of the Gross National Product (GNP) edged out their 28 percent. In 1890, manufacturing and mining at a 30 percent share of the GNP both exceeded agriculture's 19 percent share. During the same period, the percentage of workers employed in agriculture fell. Most of the nation's workers were farmers or farm laborers in 1860, but by 1900, the figure had declined to 40 percent.

Guiding Question: Why would more productive farming lead to urbanization?