The McCormick Harvesting Machine Company, formed by Cyrus Hall McCormick, merged with several other manufacturers and formed the International Harvester Co. They were primarily known for the production of harvesting equipment. They began experimenting with tractors around 1905. These tractors were huge, powerful and clumsy and although they were useful for large areas, they did not work well for the small acreage farmer.

Their first attempt at a smaller tractor was the Mogul 8-16 and was a big hit. International Harvester continued to refine their small tractor line with several follow-on models. The famous letter series tractors, including the A, B, H and M begain production in 1939.