In 1927, South Florida got its second rail line when the Seaboard Air Line Railway began operations. That railroad company's history stretches from the 19th century to today:

Although the Seaboard got its start much earlier in the form of a group of smaller railroads/railways which operated under the partnership name "Seaboard Air Line Railway"... some that date as far back as 1834, the name "Seaboard Air Line Railway" as an officially organized and formally recognized rail network dates back only as far as the year 1900 when all involved roads merged into one company.

The Seaboard Air Line Railway operated under this name until it was reorganized as the Seaboard Air Line Railroad (instead of Railway) in 1946 after and due to a period of financial problems during the depression and war years where it went into receivership. The Seaboard operated under its new name until July 1, 1967 when it merged with the Atlantic Coast Line Railroad to be come the Seaboard Coast Line Railroad. Later, in the early 1980s, the Seaboard Coast Line Railroad formed a partnership called "The Family Lines System" with a number of other railroads. These partners eventually merged to become known as the Seaboard System Railroad. Finally, in the late 1980s, the Seaboard System Railroad merged with the Chessie System Railroad to become what is known today as CSX Transportation.

Among the famous trains that ran on the SAL were the Orange Blossom Special and the Silver Meteor.

(quote from Seaboard Air Line Railroad Information Collective)