The transcontinental railroad had a profound impact on the growth of cities in the United States. By connecting the East and West coasts, the railroad made it easier for people and goods to travel between the two regions. This led to a boom in population and economic growth in many cities along the route, including Chicago.
Chicago was a small town of just a few thousand people before the railroad came to town. However, by 1870, the city's population had grown to over 200,000 people. This growth was due in large part to the railroad, which made Chicago a major hub for transportation and commerce.
Chicago's growth continued to accelerate in the decades that followed. By 1900, the city's population had reached over 1.7 million people. This made Chicago the second largest city in the United States, behind only New York City.