54 
    
    Louis Cain, ed., "Transportation", Economic Sectors, vol. 4 of Historical Statistics of the United States: Millennial Edition, 762.
                55 
    
    Greene, Horses at Work, 78.
                56 
    
    Daniel Walker Howe, What Hath God Wrought: The Transformation of America, 1815–1848 (Oxford: Oxford University Press, 2007), 214.
                57 
    
    Cain, "Transportation", Economic Sectors, vol. 4 of Historical Statistics of the United States: Milliennial Edition, 770.
                58 
    
    Там же.
                59 
    
    Albert Fishlow, American Railroads and the Transformation of the Antebellum Economy (Cambridge, MA: Harvard University Press, 1965); Robert Fogel, Railroads and American Economic Growth (Baltimore: Johns Hopkins University Press, 1964).