The origins of the Roadmaster name date to 1936 when Buick renamed its entire model lineup to celebrate the engineering improvements and design advancements over their 1935 models. Buick's Series 40 model range became the Special, the Buick Century took the place of the Series 60 and the Series 90 — Buick's largest and most luxurious vehicles — became the Limited. Buick's Series 80 became the Roadmaster, although it is commonly referred to as "sailboat", "tank", or "land yacht".
Roadmasters produced between 1936 and 1958 were built on Buick's longest wheelbase and shared its basic structure with senior Oldsmobiles. Between 1946 and 1957, the Roadmaster was Buick's premium and best appointed model, and was offered in sedan, coupe, convertible and station wagon bodystyles between 1936 and 1948.
In 1949 a hardtop coupe, designated "Riviera" joined the model line up; a four-door hardtop joined the model range in 1955. 1949 had the begings of tail fins for Buick, and Buick's new automatic transmission, the Dynaflow.
The 1953 Buick Roadmaster station wagon, Model 79-R, was the last wood-bodied station wagon mass-produced in the United States. Its body was a product of Iona Manufacturing which built all Buick station wagon bodies between 1946 and 1964. Priced at US$4,031, the wagon was second in price to the Buick Skylark.
Only 670 of these final woody wagons were produced for 1953.
In 1959, Buick again introduced a model range that represented a significant shift in its body design, and the Roadmaster was renamed the Electra.
Source: Wikipedia, 2011
Note: several shots are from Jay Leno's 1955 Roadmaster collection