level of national income if transportation somehow existed in the most efficient way possible to the absence of the railroad. He found that without the railroad, America's gross national product (GNP) would have been 7.2% less in 1890. While the largest contribution to GNP growth was made by any single innovation before 1900, this percentage only represents 2–3 years of GNP growth. Fogel makes several key assumptions and decisions in his analysis. First, his calculations comprise transportation between the primary markets of the Midwest and the secondary markets of the East and South (interregional) and transportation between cities and rural areas (intraregional). Second, he chooses to focus on the shipment of four agricultural commodities: wheat, corn, beef, and pork. Third, Fogel's social saving calculation accounts for costs not included in water rates (which include the cargo losses in transit, transshipment costs, extra wagon haulage, time lost because of slower speed, and because canals froze in the winter, and capital costs). One criticism of Fogel's analysis is that it does not account for the externalities or "spill-over" effects of the railroads, which (if included) may have increased his estimate for social savings [definition needed]. Railroads provided much of the demand for technological advances in a number of areas, including heat dynamics, combustion engineering, thermodynamics, metallurgy, civil engineering, machining, and metal fabrication. Furthermore, Fogel does not discuss the role railroads played in the development of the financial system or in attracting foreign capital, which otherwise might not have been available. Albert Fishlow Fishlow estimates that the railroad's social savings—or what he terms "direct benefits"—were higher than those calculated by Fogel. Fishlow's research may indicate that the development of railroads significantly influenced real income in the United States. Instead of Fogel's term "social saving", Fishlow uses the term "direct benefits" to describe the difference between the actual level of national income in 1859 and the theoretical level of income using the least expensive, but existing alternative means. Fishlow calculated the social savings in 1859 at 4 percent of GNP and in 1890 at 15 percent of GNP—higher than Fogel's estimate of 7.2% in 1890. Monopolies, antitrust law, and regulation Industrialists such as Cornelius Vanderbilt and Jay Gould became wealthy through railroad ownerships, as large railroad companies such as the New York Central, Grand Trunk Railway and the Southern Pacific spanned several states. In response to monopolistic practices (such as price fixing) and other