How did the different transportation systems help the North more than the South during the Civil War?

Before the Civil War, the transportation systems of the North and South were different in that the North had a vastly more developed system of railroads.  The South did not need railroads, particularly not railroads that connected many parts of the region.  Its economy depended on getting cotton to seaports, not on getting a variety of goods from each place to each other place.  This meant that there were very few railroads that truly covered a great deal of the region.  By contrast, the North was crisscrossed by tracks.

This helped the North tremendously because it allowed the North to move its troops around during the war and, perhaps more importantly, because  it allowed them to supply those troops.  The Confederacy lacked railroads and was therefore unable to keep its troops adequately supplied with all of the things they needed for fighting the war.  The North was much more capable of managing these logistics.  This mean that Northern armies had an easier  time getting  to where they needed to be and it meant that  they were better prepared to fight  when they got there because they were relatively well-fed and well-equipped.  In this way, the differences between Northern and Southern transportation really helped the North in the Civil War.