During World War II, more than 100,000 tractors were deployed and they were created by such manufacturers as Caterpillar, International Harvester, etc. The war effort was greatly aided by being able to move dirt, with the American construction effort being greatly aided by their bull dozers.
The true rewards for this high in-demand product however would not appear until after the war, while the short-time benefit was favorable marketing (growing popularity):
"Instead of near-term profits, however, manufacturers relied on less tangible, long-term rewards in the form of technological advancement, the training of laborers, and an enhanced popular depiction of the value of their brands and the work of their machines. In the post-war period, they would put these less tangible benefits to productive use when they returned to peacetime operations."