As noticed above, the cotton industry was the best example of this factory system. In 1760, this industry was overwhelming domestic system3. However, Eli Whitney, a Yale graduate working in Georgia as a private tutor, who invented the cotton gin, changed the all that. Basically, Whitney's invention revolutionized American's economy4. Reflecting to the sentence wrote by Whitney to his father, "One man and a horse will do more than fifty men with the old machines"5, factories began to dominate urban areas, and forced the United States' economy to a new level.
The increasing numbers of factory production pushed the United States toward becoming the world's greatest industrial producer and it soon demanded fast, out-reaching railroads that would enable transportation of goods which produced by factories. The historian Eric Foner said, "The development of railroads was one of the most important phenomena during the Industrial Revolution"6. The remarkable increasing of factory production resulted in the number of miles of railroad track in the United States be tripled between 1860 and 1880 and tripled again by 1920, opening new areas to commercial goods and creating a truly national market for manufactured goods7. For the flourishing of railroads industry, immigrants is an assignable factor had to be mentioned. Between 1790 and 1830, immigrants contributed only a few to the growth of the United States' populations. But between 1840 and 1860 over 4 million people entered the United States seeking for jobs and being used by American government to build the railroads8. Perhaps the greatest physical feat of 19th century America was the creation of the transcontinental railroad. Huge forces of immigrants, mainly Irish for the Union Pacific and Chinese for the Central Pacific, crossed mountains, dug tunnels and laid track9. Those large amounts of foreign workers, who should be paid, played a significant role to complete the important railroad building and to enhance the strength of the industrial economy of the United States.