The term heavyweight refers to trains consisting of passenger cars with all-steel construction, considered a great improvement in safety over the all-wooden or wood-and-steel cars of the 19th century.
By 1910, nearly all major railroads were replacing their wooden passenger fleets with cars of heavyweight construction.

Note: The history of train names on various Seaboard routes is complex, with some being temporarily replaced or discontinued for a year or two, then brought back, perhaps on a somewhat different routing (e.g., to both coasts of Florida or to only one); the following is merely a rough guide to the names of some of the major year-round trains Seaboard offered.
 Consult sources listed at the end of this article for exact details.

Before the Cross-Florida Extension from Coleman to West Palm Beach was completed in 1925 (and extended to Miami in 1927), Seaboard trains for cities on the Atlantic side of Florida were handled by the Florida East Coast Railway south of Jacksonville.

Florida and Metropolitan Limited, inaugurated January 14, 1901
Heavyweight winter-season only (December – April), all-Pullman, New York to both coasts of Florida; on January 1, 1903, renamed the Seaboard Florida Limited in winter (all first-class cars) and Seaboard Florida Express in summer; in 1930, replaced by the New York-Florida Limited, carrying coaches and Pullmans; on December 12, 1941, it was renamed the Palmland.
Reduced to New York – Columbia, S.C., in May 1968; discontinued April 30, 1971.

Atlanta Special, inaugurated 1901
Heavyweight coaches and Pullmans.
Originally a connecting train from the main-line junction of Hamlet, North Carolina, to Atlanta, in the early 1920s it began operating as a through service from Washington to Birmingham.
 It was renamed the Seaboard Express on April 12, 1903, later the Atlanta-Birmingham Special in 1911.
With the addition of air-conditioned cars on April 28, 1935, it was renamed the Robert E. Lee, and on May 18, 1947, the Cotton Blossom.
On April 24, 1955, the name was dropped, and it continued as a mail and express train until discontinued in 1968.

Suwanee River Special, inaugurated November 8, 1921
Heavyweight coaches and Pullmans.
This train carried passengers from Cincinnati and other Midwest points to the Gulf Coast resort cities of Tampa, St. Petersburg, Venice, and Naples.
Handled by Southern Railway (U.S.) from Cincinnati via Atlanta to a connection with the Seaboard at Hampton, Florida.
North of Cincinnati, Pullmans handled by other railroads provided through sleeping-car service to and from Chicago, Detroit, and Cleveland.

New Orleans-Florida Limited, November 1924 – July 1949
Heavyweight coaches and Pullmans.
From 1924 to 1929, this train carried the first and only transcontinental sleeping car in the United States, a Pullman from Jacksonville to Los Angeles via a connection with the Southern Pacific Railroad's Sunset Limited at New Orleans.
Superseded by the streamlined Gulf Wind (see below).

Cross Florida Day Service, Cross Florida Night Service, 1925-early 1960s
began with a 1925 predecessor (Cross Florida Night Limited); 1930 – early 1960s St. Petersburg – Miami; day service: bus: St. Petersburg – West Lake Wales, train: West Lake Wales – Miami; night service: coaches: St. Petersburg-Tampa, Tampa-West Lake Wales, West Lake Wales-Miami, sleepers: Tampa-Miami
Orange Blossom Special, November 21, 1925 – April 26, 1953; due to wartime restrictions, did not run in the years 1942–1945.

Heavyweight, winter-season only, all-Pullman, New York to Tampa/St.
Petersburg, and West Palm Beach, later to Miami as well.
The most luxurious SAL train of its time, introduced to entice wealthy tourists and businessmen to Florida during the land-boom era, its deluxe features included fresh flowers and fresh fish for the dining car, a library car and observation car, and a club car with a barber and shower bath.
The OBS was later immortalized in a very famous fiddle tune of the same name.

Southern States Special, inaugurated May 5, 1929
Heavyweight coaches and Pullmans, New York to Florida; renamed t
The term heavyweight refers to trains consisting of passenger cars with all-steel construction, considered a great improvement in safety over the all-wooden or wood-and-steel cars of the 19th century. By 1910, nearly all major railroads were replacing their wooden passenger fleets with cars of heavyweight construction.
Note: The history of train names on various Seaboard routes is complex, with some being temporarily replaced or discontinued for a year or two, then brought back, perhaps on a somewhat different routing (e.g., to both coasts of Florida or to only one); the following is merely a rough guide to the names of some of the major year-round trains Seaboard offered.  Consult sources listed at the end of this article for exact details.
Before the Cross-Florida Extension from Coleman to West Palm Beach was completed in 1925 (and extended to Miami in 1927), Seaboard trains for cities on the Atlantic side of Florida were handled by the Florida East Coast Railway south of Jacksonville.
Florida and Metropolitan Limited, inaugurated January 14, 1901
Heavyweight winter-season only (December – April), all-Pullman, New York to both coasts of Florida; on January 1, 1903, renamed the Seaboard Florida Limited in winter (all first-class cars) and Seaboard Florida Express in summer; in 1930, replaced by the New York-Florida Limited, carrying coaches and Pullmans; on December 12, 1941, it was renamed the Palmland. Reduced to New York – Columbia, S.C., in May 1968; discontinued April 30, 1971.
Atlanta Special, inaugurated 1901
Heavyweight coaches and Pullmans. Originally a connecting train from the main-line junction of Hamlet, North Carolina, to Atlanta, in the early 1920s it began operating as a through service from Washington to Birmingham.  It was renamed the Seaboard Express on April 12, 1903, later the Atlanta-Birmingham Special in 1911. With the addition of air-conditioned cars on April 28, 1935, it was renamed the Robert E. Lee, and on May 18, 1947, the Cotton Blossom. On April 24, 1955, the name was dropped, and it continued as a mail and express train until discontinued in 1968.
Suwanee River Special, inaugurated November 8, 1921
Heavyweight coaches and Pullmans. This train carried passengers from Cincinnati and other Midwest points to the Gulf Coast resort cities of Tampa, St. Petersburg, Venice, and Naples. Handled by Southern Railway (U.S.) from Cincinnati via Atlanta to a connection with the Seaboard at Hampton, Florida. North of Cincinnati, Pullmans handled by other railroads provided through sleeping-car service to and from Chicago, Detroit, and Cleveland.
New Orleans-Florida Limited, November 1924 – July 1949
Heavyweight coaches and Pullmans. From 1924 to 1929, this train carried the first and only transcontinental sleeping car in the United States, a Pullman from Jacksonville to Los Angeles via a connection with the Southern Pacific Railroad's Sunset Limited at New Orleans. Superseded by the streamlined Gulf Wind (see below).
Cross Florida Day Service, Cross Florida Night Service, 1925-early 1960s
began with a 1925 predecessor (Cross Florida Night Limited); 1930 – early 1960s St. Petersburg – Miami; day service: bus: St. Petersburg – West Lake Wales, train: West Lake Wales – Miami; night service: coaches: St. Petersburg-Tampa, Tampa-West Lake Wales, West Lake Wales-Miami, sleepers: Tampa-Miami
Orange Blossom Special, November 21, 1925 – April 26, 1953; due to wartime restrictions, did not run in the years 1942–1945.
Heavyweight, winter-season only, all-Pullman, New York to Tampa/St. Petersburg, and West Palm Beach, later to Miami as well. The most luxurious SAL train of its time, introduced to entice wealthy tourists and businessmen to Florida during the land-boom era, its deluxe features included fresh flowers and fresh fish for the dining car, a library car and observation car, and a club car with a barber and shower bath. The OBS was later immortalized in a very famous fiddle tune of the same name.
Southern States Special, inaugurated May 5, 1929
Heavyweight coaches and Pullmans, New York to Florida; renamed t
Seaboard Air Line Railroad