The Lower Mississippi River Valley was the most critical theater of the Civil War. The Mississippi River served as the major interstate highway of 19th-century America. The river enabled people to transport goods from St. Louis and Pittsburgh through New Orleans to the world. Rivers were extremely valuable as transportation networks, but beginning in the 1840s, railroad construction linked major cities that were unconnected by water. Both sides realized the significance of these transportation networks and knew they must control them to win the war.
