<span>The railroads had to pass through mountains and rivers.</span>
They helped more people to construct there own business they were also were able to ships goods as well. Without railroads they would have a hard time shipping goods
The process of reconstructing the Union began in 1863, two years before the Confederacy formally surrendered. After major Union victories at Gettysburg and Vicksburg, Abraham Lincoln issued the Proclamation of Amnesty and Reconstruction in which he outlined his Ten-Percent Plan. The plan stipulated that each secessionist state had to redraft its constitution and could reenter the Union only after 10 percent of its eligible voters pledged an oath of allegiance to the United States.
Put simply the hydro electric dam has provide the area with power so it can grow and improve as well as acting as a water resew are in some case.
Hope this helps <span />
Phillipenes, Cuba, Puerto rico, hati, Jamaica. If I'm wrong I'm sorry if im wrong.