Why did the united states want to stop the spread of communism after world war two?

Why did the south decide to fight a defensive war 1.to protect their plantations 2.to make the north look like the aggressor 3.to take advantage of their knowledge of the land 4.to make maximum use of the limited transport system

What did the u.s. want to build on the land acquired through the gadsden purchase?

When was the us construction written