A form of the "Dow Jones Index" has been around since 1884. The original "Dow Dozen" included railroads, but it soon evolved into the "Transportation Index" made up of railroads, the most important large companies of the time. The more famous "Industrial Index" then began, and ulitmately became the most-watched index in America.

Over the years, companies have come and gone. Consequently, the makeup of both the transportation index and the industrials index has changed constantly. Please check Dow Jones index for a more in-depth information and listing of every railroad company that I can find.