The vehicle in the movie The Polar Express is a train. More specifically, it is a steam-powered passenger train that carries children from their homes to the North Pole on Christmas Eve.
The 2004 computer-animated film adapts Chris Van Allsburg’s 1985 picture book. Its train is led by a locomotive and followed by passenger cars, so “train” is the complete vehicle category; “locomotive” would describe only the engine at the front.
The film’s locomotive was modeled in part on Pere Marquette 1225, a real 2-8-4 Berkshire steam locomotive preserved in Michigan. Van Allsburg had encountered the engine as a child, and its number suggested the date 12/25—Christmas Day.
The train’s journey is magical rather than realistic: it travels through snowy landscapes, across dangerous ice, and finally reaches the North Pole. The story’s real-world popularity has also inspired licensed Polar Express holiday train rides in the United States, Canada, and the United Kingdom.