A circus train is a method of conveyance for circus troupes. Circus trains began in the 1870s, by replacing the shows that moved by slow animal-drawn wagons. Over the years these trains grew in length as the train cars switched from wood to steel construction. Circus trains typically consisted of three types of cars: large animal cars, flat cars loaded with colorful wagons and passenger cars for the workers and performers. They were usually found in the train in that order. Circus cars were generally longer than normal freight cars because the railroads charged by the car & mile. They were painted very colorful to attract attention. The greatest number of circus trains operated between 1920 and 1950. Over those years many merged and others went broke. One of the larger users of circus trains was the Ringling Bros. and Barnum & Bailey Circus (RBBX), a famous American circus formed when the Ringling Brothers Circus purchased the Barnum and Bailey Circus in 1907.
When the circus switched to travel by train, they began by using flatcars from the Pennsylvania Railroad, which turned out to be hazardous because the Pennsylvania Railroad’s cars were in poor shape. In mid-season it was decided that they would buy their own cars, and when the P.T. Barnum Circus left Columbus, Ohio, it traveled on the first circus-owned train. It was made up of 60 cars, including 19–45 flatcars carrying about 100 wagons. Circus trains have proven well-suited for the transportation of heavy equipment (tents, rolling wagons, vehicles and machinery) and animals (elephants, lions, tigers and horses), despite tragic accidents over the years.
It is common practice for model railroaders to enact the operation of the circus train on model railroads using the O scale layout with an operating circus train, several displays, and a parade staged in a town.