The Association of American Railroads (AAR) is an industry trade group representing primarily the major freight railroads of North America. Amtrak and some regional commuter railroads are also members. Smaller freight railroads are typically represented by the American Short Line and Regional Railroad Association (ASLRRA), although some smaller railroads and railroad holding companies are also members of the AAR. The AAR also has two associate programs, and most associates are suppliers to the railroad industry.
The Iowa Interstate Railroad is a Class II regional railroad operating in the central United States. The railroad is owned by Railroad Development Corporation of Pittsburgh, Pennsylvania.
Genesee & Wyoming Inc. (G&W) is an American short line railroad holding company, that owns or maintains an interest in 122 railroads in the United States, Canada, Belgium, Netherlands, Poland, and the United Kingdom; and formerly in Australia.
The Virginia Port Authority (VPA) is an autonomous agency of the Commonwealth of Virginia that owns The Port of Virginia, a group of facilities with their activity centered on the harbor of Hampton Roads, Virginia.
The following is a brief history of the North American rail system, mainly through major changes to Class I railroads, the largest class by operating revenue.