The primary industry that fueled the growth of the Transcontinental Railroad was the transportation of goods, particularly agricultural products and natural resources, such as timber, coal, and metals. The expansion of the railroad network facilitated trade and commerce across vast distances, connecting the East and West Coasts of the United States. This revolutionized not only the economy but also encouraged westward expansion, migration, and settlement in previously inaccessible areas. Moreover, it played a pivotal role in shaping the American economy during the late 19th century, enhancing industry and fostering economic development.