In 1878, Porter Slate and Dan Best built a steam-powered machine to push Slate's grain combine. Over a period of three years, they built five different machines, each an improvement over it's predecessor. The final version had rubber belts over the drive wheels, forming a type of track system.

 

In 1881 Best, with Slates blessing, took the ideas they had developed and began a career that eventually led into the manufacturing of the Best Track-Type Tractor. In 1925, Holt merged with Best to form the Caterpillar Tractor Company.