Advantages of the use of mechanical harvesting machines in the USA:

The dramatic expansion was made possible by new technology. Through the nineteenth century, as the settlers moved into new habitats and new lands they modified their implements to meet their requirement. In 1831, Cyrus McCormick invented the first mechanical reaper which could cut in one day as much as five men could cut with cradles and 16 men with sickles. For the big farmers of the Great Plains these machines had many attractions. The new machines allowed the big farmers to rapidly clear large tracts, break up the soil, remove the grass and prepare the ground for cultivation. The work could be done quickly and with a minimal number of hands. With power-driven machinery four men could plough, seed and harvest 2000 to 4000 acres of wheat in a season.

Disadvantages of the use of mechanical harvesting machines in the USA:

For the poorer farmers, machines brought misery. Many of them bought these machines, imagining that wheat prices would remain high and profits would flow in. If they had no money, the banks offered loans. Those who borrowed found it difficult to pay back their debts. Many of them deserted their farms and looked for jobs elsewhere. Mechanization had reduced the need for labor. And the boom of the nineteenth and early twentieth centuries seemed to have come to an end by the mid-1920s. After that even most of the rich farmers faced trouble. Production had expanded so rapidly during the war and post-war years that there was a large surplus. Unsold socks piled up, storehouses overflowed with grain, and vast amounts of corn and wheat were turned into animal feed. Wheat prices fell and export markets collapsed. This created the ground for the Great Agrarian Depression of the 1930s that ruined wheat farmers everywhere.