standard historical interpretation holds that the railroads were central to the development of a national market in the United States and served as a model of how to organize, finance and manage a large corporation, along with allowing growth of the American population outside of the eastern regions. Take-off Thesis In 1944, American economic historian Leland Jenks (having conducted an analysis based on Joseph Schumpeter's theory of innovation) similarly claims that railroads had a direct impact on the growth of the United States' real income and an indirect impact on its economic expansion. In his Rostovian Take-off Thesis, Walt W. Rostow systematically developed the Jenks model that railroads were crucial to American economic growth. According to Rostow, railroads were responsible for the "take-off" of American industrialization in the period of 1843–1860. This "take-off" in economic growth occurred because the railroad helped to decrease transportation costs, transport new products and goods to commercial markets, and generally widen the market. Furthermore, the development of railroads stimulated the growth of the modern coal, iron, and engineering industries, all of which were essential for wider economic growth. According to Rostow's Take-off Thesis, railroads generated new investment, which simultaneously helped develop financial markets in the United States. Contemporary American economic historians have challenged this conventional view. The respective findings of Robert Fogel and Albert Fishlow do not support Rostow's claim that railroads stimulated widespread industrialization by increasing demand for coal, iron, and machinery. Drawing upon historical data, Robert Fogel found that the impact of railroads on the iron and steel industries was minimal: from 1840 to 1860, railroad production used less than five percent of the total pig iron produced. In addition, Fogel argues, only six percent of total coal production from 1840 to 1860 was consumed by railroads through consumption of iron products. Like Fogel, Fishlow showed that most railroads used very little coal during this time period because they were able to burn wood instead. Fishlow also found that iron used by railroads was only 20% of net consumption in the 1850s. Fogel and "essential" issue Fogel concludes that railroads were important but not "essential" to late 19th-century growth in the U.S. in the sense that a possible alternative existed even if it was never tried. Fogel focuses on the "social saving" created by railroads, which he defines as the difference between the actual level of national income in 1890 and the theoretical