CSX Transportation, known colloquially as simply CSX, is a Class I freight railroad company operating in the Eastern United States and the Canadian provinces of Ontario and Quebec. The railroad operates on approximately 21,000 route miles of track.

CSX Transportation is one of the leading Class I freight railroads in North America, primarily serving the eastern United States and parts of Canada. Headquartered in Jacksonville, Florida, the company operates a massive network encompassing approximately 20,000 route miles of track across 26 states, the District of Columbia, and the provinces of Ontario and Quebec. CSX was formed in 1980 through the merger of the Chessie System and Seaboard Coast Line Industries, and it remains a critical pillar of the American supply chain. The railroad transports a diverse range of commodities, including coal, agricultural products, automobiles, chemicals, and intermodal containers. Because nearly two-thirds of the American population lives within its service territory, CSX plays a vital role in moving goods from major ports on the Atlantic and Gulf Coasts to inland markets. It is often compared to its primary eastern rival, Norfolk Southern, as they are the two dominant rail systems in the East.