In the United States, railroads are designated as Class I, Class II, or Class III, according to size criteria first established by the Interstate Commerce Commission (ICC) in 1911, and now governed by the Surface Transportation Board (STB). The STB's current definition of a Class I railroad was set in 1992, that being any carrier earning annual revenue greater than $250 million. The threshold was reported to be $289.4 million in 2023.^[1]

This is a list of current and former Class I railroads in North America under the older criteria and the newer as well as today's much different post-railroad consolidation classifications.

As of 2023^[update] there are just four American owned Class I freight railroad companies and one passenger railroad company (Amtrak). The list also includes two Canadian-owned Class I freight railroads, both of which have trackage in the US, and one, CPKC, has trackage in Mexico.^[1][2]

• Amtrak
• BNSF Railway
• Canadian National Railway
• Canadian Pacific Kansas City
• CSX Transportation
• Norfolk Southern Railway
• Union Pacific Railroad

This section does not cite any sources. (December 2023)

This list includes diverse financial entities. Some of these refer to operating companies which were turned into investments, some hanging onto a corporate skeleton owning properties as holding companies, or have assigned their properties in mergers, bankruptcy or other legal acts (dissolution of the corporation), and others defunct and dismantled.