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.

they required less loading and unloading

explanation:

the shipping container improved shipping because it cut down on unloading time by three weeks, eliminated wasted space, and allowed ships to carry.

nuclear fission produces the atomic bomb, a weapon of mass destruction that uses power released by the splitting of atomic nuclei the fighting in iwo jima and okinawa affected the allies' pacific strategy because truman decided to drop the atomic bomb on mainland japan.