structural:reformatting, quality:corruption, information:filtering, stylistic:style_transfer
Aschauer's model and other academic approaches

According to an overview of multiple studies by Louis Cain, the infrastructure investments have also been profitable. For example, Fogel estimated the private rate of return on the Union Pacific Railroad at 11.6%, whereas the social rate that accounts for social benefits, such as improved firm efficiencies and government subsidies, was estimated at 29.9%. In another study, Heckelman and Wallis estimated that the first 500 miles of railroad in a given state led to major increases in property values between 1850 and 1910. They calculated the revenue gain from the land appreciation to be $33,000-$200,000 per mile, while construction costs were $20,000-$40,000 per mile. Hence, on average the revenue from construction of a new railroad outweighed the costs. While initial construction returns were high, the profitability diminished after the first 500 miles.