The originator of SCL was the former Seaboard Air Line Railroad, which previously merged with the Atlantic Coast Line Railroad in 1967 to form the Seaboard Coast Line. In later years, it merged with the Louisville & Nashville Railroad, as well as several smaller subsidiaries such as the Clinchfield Railroad, Atlanta & West Point Railroad, Monon Railroad and the Georgia Railroad. From the late 1970s onward these railroads were known collectively as the Family Lines. In 1982, they were merged into a single railroad, the Seaboard System Railroad.