A vestibuled train is a passenger train whose cars are connected by enclosed vestibules and flexible gangways, offering safe and comfortable passage between cars, a significant improvement over earlier open platforms. The first such train was introduced on June 15, 1887, by the Pennsylvania Railroad on its Pennsylvania Limited, with a viable design developed by H. H. Sessions and his staff at Pullman Car Works.

Prior to this innovation, moving between train cars was dangerous, exposing passengers to the elements and locomotive exhaust, which often confined them to a single car during their journey. Vestibuled trains revolutionized rail travel by allowing passengers to move freely throughout a "continuous unit," leading to the widespread adoption of specialized cars like dining cars, lounge cars, and sleeping cars. This advancement was crucial for ushering in the "golden age" of rail travel, enabling luxury trains such as the 20th Century Limited and Broadway Limited to offer unprecedented comfort and convenience.