It is not hard to discern how this happened.  At the beginning of the 20th Century, the industry relied upon horses and mules for the heavy lifting around the farm; these animals, which required care and feeding as well, were replaced by about 5 million tractors and other vehicles and implements. This mechanization, along with improved methodologies, has driven farm consolidation; while the number of farms in the USA has dropped 63%, the average farm size has increased by 67%.  Additionally, in 1930, about one-third of farmers earned off-farm income; 70 years later, that number was 93%. The impact on rural American has not only been devastating in terms of population, but culture.  In 1900, about 60% of rural Americans were farmers; the number is about 20% now, and 10% in BB.  Once culturally dominate in rural communities, they are now relegated to the sidelines.
Source: Fort Scott Biz