Seaboard System Railroad

The Seaboard System Railroad, Inc. (reporting markSBD) or The Seaboard System Railroad was a short-lived American Class I railroad that operated from 1982 to 1986 in the Southeastern United States.

Since the late 1960s, Seaboard Coast Line Industries had operated the Seaboard Coast Line and its sister railroads—notably the Louisville & Nashville and Clinchfield—as the "Family Lines System". In 1980, SCLI merged with the Chessie System to create the holding company CSX Corporation; two years later, CSX merged the Family Lines railroads to create the Seaboard System Railroad.

In 1986, Seaboard renamed itself CSX Transportation, which absorbed the Chessie System's two major railroads the following year.