Why did americans “dream” of linking the atlantic and pacific oceans by rail, as the author states?

Linking the Atlantic and Pacific oceans is called a transcontinental railway. This is a means to make trade and commerce easier and faster. These railroads will open a lot of opportunities for the western world to explore the rich countries of the east. It will open unpopulated regions and allow for the west to create networks within the Asian and Atlantic continents.

c 3 branches because idk why they had 3 well when:

you think of it there are still contrys with 3