Railroad expansion refers to the growth and development of railway networks, particularly during the 19th and early 20th centuries. This expansion allowed for faster transportation of goods and people across vast distances, connecting cities and rural areas. Key projects, such as the Transcontinental Railroad in the United States, played a significant role in facilitating trade and migration. The expansion of railroads also contributed to economic growth by creating jobs and stimulating industries like steel and coal. Additionally, it helped shape the development of towns and cities, as new rail lines often led to increased settlement and commerce in previously remote areas.