The Seaboard System Railroad was a former Class I railroad

Class I railroad

A Class I railroad in the United States and Mexico, or a Class I rail carrier in Canada, is a large freight railroad company, as classified based on operating revenue.Smaller railroads are classified as Class II and Class III...

 created by merging the railroads of the Family Lines System. Although sharing common ownership, the railroads of the Family Lines System used different names when conducting business. In order to alleviate confusion and facilitate the eventual merger of the railroad subsidiaries of CSX Corporation

CSX Corporation

CSX Corporation was formed in 1980 by the merger of Chessie System and Seaboard Coast Line Industries and eventually merged the various railroads owned by those predecessors into a single line that became known as CSX Transportation. Based in Richmond, Virginia, USA after the merger, in 2003...

, the Seaboard System was created effective January 1, 1983. The company was merged on July 1, 1986 with the Chessie System

Chessie System

Chessie System, Inc. was a holding company that owned the Chesapeake and Ohio Railway , the Baltimore and Ohio Railroad , the Western Maryland Railway , and several smaller carriers. It was incorporated in Virginia on February 26, 1973, and it acquired the C&O on June 15...

 to form CSX Transportation

CSX Transportation

CSX Transportation operates a Class I railroad in the United States known as the CSX Railroad. It is the main subsidiary of the CSX Corporation. The company is headquartered in Jacksonville, Florida, and owns approximately 21,000 route miles...

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The Seaboard's roots were in Seaboard Coast Line Industries

Seaboard Coast Line Industries

Seaboard Coast Line Industries, Inc., incorporated in Delaware on May 9, 1969, was a railroad holding company that owned the Seaboard Coast Line Railroad, its subsidiary Louisville and Nashville Railroad, and several smaller carriers. Its railroad subsidiaries were collectively known as the Family...

, a holding company created in 1972 in order to combine the SCL's subsidiary railroads into a single entity.