Final answer:
Agriculture in the United States was transformed most in the second half of the 19th century by the Industrial Revolution, which facilitated a shift from agrarian to industrial economies and introduced significant technological advancements in farming and manufacturing productivity.
Step-by-step explanation:
In the second half of the 19th century, agriculture in the United States was transformed most by the Industrial Revolution. This period marked a shift from a primarily agrarian economy to an industrial economy, with new technologies paving the way for massive leaps in industrialization. The Industrial Revolution saw the introduction of power-driven machinery such as the steam engine, the power loom, and the steam locomotive, which greatly enhanced productivity in agriculture as well as in manufacturing. These technological advancements allowed for a dramatic restructuring in the way agricultural and industrial production was carried out, leading to increased efficiency and production capacities.
By 1870, while the United States was still largely agricultural, the next fifty years would see a significant transition as industrial jobs in cities became more attractive compared to farming. The Industrial Revolution played a pivotal role in transforming American society by introducing technologies that increased farm productivity, and by providing opportunities that drew people to urban centers for factory work, further spurring urbanization.
As a result of these changes, by the late 1800s and early 20th century, more Americans were involved in industrial labor, and urban populations had grown significantly. Hence, the transformation of American agriculture was deeply linked to the wider context of industrialization and its socio-economic impacts on American life.