Both the number and the percentage of people in the United States involved in nonagricultural pursuit expanded rapidly during the half century following the Civil War, with some of the most dramatic increases occurring in the domains of transportation, manufacturing and trade and distribution. The development of the railroad and telegraph systems during the middle of the nineteenth century led to significant improvements in the speed, volume, and regularity of shipments and communications, making possible a fundamental transformation in the production and distribution of goods. In agriculture, the transformation was marked by the emergence of the grain elevators, the cotton presses, the warehouses, and the commodity exchanges that seemed to so many of the nation's farmers the visible sign of a vast conspiracy against them. In manufacturing, the transformation was marked by the emergence of a 'new factory system' in which plants became larger, more complex, and more systematically organized and managed. And in distribution, the transformation was marked by the emergence of the jobber(中间商), the wholesaler, and 'the mass retailer(零售商). These changes radically altered the nature of work during the half century between 1870 and 1920. To be sure, there were still small workshops, where skilled craftspeople manufactured products ranging from newspapers to cabinets to plumbing fixtures. There were the sweatshops in city tenements, where groups of men and women in household settings manufactured clothing or cigars on a piecework basis. And there were factories in occupations such as metalwork where individual contractors presided over what were essentially handicraft proprietorships that coexisted within a single building. But as the number of wage earners in manufacturing rose from 2.7 million in 1888 to 4.5 million in 1900 to 8.4 million in 1920, the number of huge plants like the Baldwin Locomotive Works in Philadelphia burgeoned (迅速成长), as did the size of average plant. (The Baldwin Works had 600 employees in 1855, 3,000 in 1875, and 8,000 in 1900.) By 1920, at least in the northeastern United States where most of the nation's manufacturing wage earners were concentrated, three-quarters of those worked in factories with more than 100 employees and 30 percent worked in factories with more than 100 employees. What can be inferred from the passage about the agricultural sector of the economy after the Civil War?______