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 fall of the Roman Empire
Citizens 18 and older can vote , you don’t have to pay a poll tax to vote .
I believe the answer is Transportation Innovations
The answer i believe is the letter d
