Currently the 4 big railroads are Union Pacific, BNSF, Norfolk Southern, and CSX. However they are often criticized for being monopolistic and having a chokehold on freight transport. The US used to have a fifth railroad rivaling their size, Conrail, but it was bought in 1998.
@CromlynGames Yes. Big would be $6 billion in annual revenue and US based, so Canadian railroads don’t count.
@Yoav in the case of the post 2021 merger of Canadian South Pacific, that company operates on rail between Canada and Mexico. Where do we say it is based?
The other 'Canadian' railroad has, by squinting at the map, at least a third of its rail within USA borders. Do we count a third of its revenue? (Or do you just modify market to an extra railroad in the north American system?)
I finally submit a wildcard. New York Metro system is a rail company with $8bn plus turnover. Not the intention of your market, but I suggest rules as currently written you must resolve yes.
@CromlynGames US based means majority of trackage within the US. According to this site and Wikipedia the combined CP KCS railroad would have ~22.7k miles of trackage total and
@Yoav ~10.9k in the US, which would be just under half, so it wouldn’t count.
I won’t count the New York Metro because I don’t think it ever transported freight, and the spirit of the question refers to freight company who get the vast majority of their revenue from freight.