In the 19th century, as the United States spread across the continent, transportation systems helped connect the growing nation. First rivers and roads and then canals and railroads moved travelers and agricultural and manufactured goods between farms, towns, and cities.

Transportation was the primary engine of American westward expansion, transforming the nation from a coastal collection of colonies into a transcontinental power. In the early 19th century, the development of canals (like the Erie Canal) and steamboats drastically reduced the cost and time of moving goods and people across the Appalachian Mountains, sparking the growth of inland hubs like Chicago and St. Louis. The real revolution, however, came with the First Transcontinental Railroad, completed in 1869, which replaced months of dangerous wagon travel with a reliable one-week journey. This allowed for the rapid settlement of the Great Plains, the extraction of western resources like gold and timber, and the creation of a unified national market. While these technologies facilitated economic prosperity and migration for millions, they also played a central role in the systematic displacement of Native American tribes and the intensification of the slavery-based "Cotton Kingdom" in the South. Ultimately, transportation didn't just move people; it projected federal authority and industrial capitalism into the furthest reaches of the continent.