When Henry Varnum Poor published "History of Railroads and Canals in the United States" in 1860, he started something. That publication was the framework for what soon became the credit rating agency model. John Moody and Company jumped on board in 1900 with the first "Moody's Manual of Industrial and Miscellaneous Securities" and in 1909, Moody decided to put a letter-grade rating on railroad bonds so investors could better understand their investment options.