Final answer:
The major change that took place in the U.S. economy during the mid-1800s was workers moving to cities to work in factories during the Industrial Revolution.
Step-by-step explanation:
The major change that took place in the U.S. economy during the mid-1800s was that workers began moving to cities to work in factories. This period is known as the Industrial Revolution, and it involved a shift from predominantly agricultural societies to industrialized ones.
This change was driven by advancements in technology, such as the invention of the steam engine and the increase in factory production. Workers moved to cities in search of employment opportunities and better wages, as factories offered more jobs than the traditional farming sector.
As a result, cities expanded rapidly, and urbanization became a prominent feature of the mid-1800s. This shift also led to other changes in society, including the rise of labor movements and the growth of a middle class.
Learn more about changes in the U.S. economy during the mid-1800s