Prior to 1949, Plymouth had offered only a 4-door "woodie" station wagon, which was expensive not only to build, but also to buy. In 1949, Plymouth revolutionized the US station wagon market by introducing the industry's first all-steel body station wagon, the Suburban. In addition, for the first time in a low-priced car, automatic "turn-the-key" ignition/starter combination was introduced. The Suburban featured a two-door body (plus tailgate) and seated six. The back row of seating folded flat to allow 42 inches (1,100 mm) of flat floor space, and became popular as a commercial wagon.
Source: Wikipedia, 2013