Early in the history of agriculture, draft animals replaced humans for such difficult tasks as plowing and pulling heavy loads. More recently, machines have replaced animals in many parts of the world. The most familiar farm machine is the tractor.

The steam tractor was developed in response to the increase in the size of farms during the westward expansion of the United States and Canada. The Case company built the first steam tractor in 1829. Several other companies soon followed with their own machines. Steam tractors (then called portable traction motors or agricultural motors) were extremely large and heavy. The boiler had to be made of cast-iron to contain the heat, and the wheels had to be large and heavy to carry the weight. These tractors were often owned by contractors who offered their services over a certain territory. The tractor would be driven to the edge of the...