Urbanization and Railroads in 19th Century America

During the late 19th century, the United States experienced significant urbanization, with many people migrating from rural areas to cities in search of jobs and better living conditions. This shift brought about numerous changes in social, economic, and cultural dynamics. One of the most notable factors that contributed to the rapid growth of cities during this period was the rise of industries that spurred population movements. Which of the following industries was primarily responsible for driving urbanization in America during this time?