Where were the first american railroads buit?

Baltimore

Explanation:

On February 28, 1827, the Baltimore & Ohio Railroad became the first U. S. railway chartered for commercial transport of passengers and freight. There were skeptics who doubted that a steam engine could work along steep, winding grades, but the Tom Thumb, designed by Peter Cooper, put an end to their doubts. Investors hoped a railroad would allow Baltimore, the second largest U. S. city at the time, to successfully compete with New York for western trade.