Solid earnings in a shaky economy is one reason. The emerging picture of a growth industry is another. In a shaky economy, the railroads have been able to produce solid earnings, consistently outperforming financial barometers like the Dow Jones Industrial Average and the S&P 500. During the past six months, as the U.S. economy has gradually and painfully emerged from the Great Recession, the price of railroad stocks has grown up to twice as fast as the Dow.