Diesel-electric locomotive

Train enthusiasts often talk of a train's gauge, and by this term, they refer to the distance between the inner rails of the train track. Gauges 1, 2, 3, and 4, pertain to European-made trains, except that American train maker Ives & Co. produced its first trains in a 1 gauge. Trains made in a standard gauge, measuring 2.125 inches between rails, became popular in the early years of the 20th century. By the Great Depression, however, the smaller, less expensive O-gauge trains better suited American wallets.