Railroads helped armies to cross the Smoky Mountains between Chattanooga, TN and Atlanta, GA. This became a war winning line of march that brought Sherman’s Army into the heart of the South.
The telegraph helped with the news spreading around to report on the war. During the war, the telegraph was only military use only.
The invenion of photography allowed families to have a keepsakes of family members in the war. Photography also enhanced the image of political figures which was good for elections.
Weapons were very important in the war of course, and out of all the technological advances, the rifle was most important. After the Civil War began, there was a mass production of rifles instead of muskets.
Textiles were important because as the fighting wore on, supplies on both sides became scarce. And the two governments squeezed textile factories, like the cottage industries, for all that it was worth.