The railroad sector offers retail investors the relative security of being in a historically important industry that is vital to the U.S. economy. The great benefit of investing in the railroad sector is that the railroads themselves have a lot of market security. After all, Berkshire Hathaway's BNSF and Union Pacific are effectively a duopoly in the West, and CSX and Norfolk Southern are similar in the East, while Canadian Pacific and Canadian National dominate Canada, and the far smaller Kansas City Southern runs routes through the South and Mexico.
Together, these seven railroads generate more than $90 billion in annual revenue. They are categorized as Class I railroads by the Surface Transportation Board (STB), and they account for the majority of freight rail activity in the U.S. The good news is that you can invest in each and every one of them.
In case you are wondering, Class I railroads are defined by the STB as those with annual revenue greater than $447.6 million. They are regulated by the STB and are obliged to file "annual and periodic financial and statistical reports," according to the organization. For reference, Class II railroads are classified as those with annual revenue of between $35.8 million and $447.6 million, but unfortunately, there is no direct way to invest in them. It's a similar situation with Class III railroads, which are classified as generating less than $35.8 million in annual revenue.
Source Fool.com