Mostly due to the ideas of Manifest Destiny. They started going westwards with the desire to span the United States from coast to coast, and then they started going worldwide. The idea behind it is that the United States were destined to help the world become free and democratic like they were so they started helping people worldwide in rebellions against colonialism or in similar affairs.
The answer is the last one, " Atlantic Ocean to the Pacific Ocean".
I think 6 days
During this infamous trek, known as the “Bataan Death March,” the prisoners were forced to march 85 miles in six days, with only one meal of rice during the entire journey.