“Influence of Railroads Upon Agriculture,” Agriculture of the United States, 1860.

Far from eliminating animal power as a source of energy, the dramatic expansion of the railroad system sharply increased the number of horses in the United States. According to this short essay from the 1860 agricultural census, the number of horses in the country increased by fifty-one percent between 1840 and 1860. Most of this growth occurred during the most rapid period of railroad expansion. 
 
Why do you think that the number of horses increased with the spread of railroads? What does the relationship between horses and railroads suggest about how new technologies might interact with older energy sources?
Citation: 
U.S. Census Office. Agriculture of the United States in 1860; Compiled from the Original Returns of the Eighth Census, Under the Direction of the Secretary of the Interior, By Joseph C.G. Kennedy. New York: Norman Ross Publishing, 1864.
Library Item date: 
1860