Because the US had a great geographical location which shileded them from immediate contact with any military force. This was one thing, another thing was that they were lending money to the different European nations which they had to return after some time. All of this enabled the US to catapult itself and become a world power.
Steam was used for boats and trains, making cleaner, faster transportation.
The sales tax is regarded by some people as a(n) ___regressive tax____ tax.