The Seaboard System Railroad, Inc. (reporting mark SBD) was a US Class I railroad that operated from 1982 to 1986. 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.