Answer:
There were several factors that led to the Rapid Industrialization of United States in the 1800s.
The two major factors were the development of the Steam Engine and Cheap labor in the post civil-war Era .
Explanation:
The invention of the Steam Engine changed everything. Not only did it make transport easier and cheaper for everyone, it helped to introduce mechanized manufacturing and farming. This gave rise to a consumer culture never seen people in the history of human kind.
Also, after the Civil War ended, and the reconstruction era saw the availability of cheap labor and not to mention thousands of migrants who had come to the US for better lives.
All of this contributed to rapid economic growth, westward expansion, urbanization and industrialization.