People in the unites States traveled by the railroad in the 1800s because it was the cheapest form of travel in the country. Thus, the correct answer is A.
The railroad network made traveling across the country easier, faster, and less expensive. This helps to improve communication amongst residents in different parts of the country.
The railways help to reduce the cost of carrying goods over long distances. These were very essential for the industrialization of the country. This helps in increasing productivity which seems as incredible to achieve growth.
Therefore, option A shows the cheapest form of travel is the appropriate answer.
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