The worst maritime disaster in US maritime history occurred on April 27, 1865, when the SS Sultana exploded on the Mississippi River killing 1,168 people.
The SS Sultana was a side-wheel commercial steamboat constructed out of wood normally tasked with transportation in the lower Mississippi. Even though it only had a capacity of 376 passengers, on the day of the tragedy the steamboat was carrying 2,137 passengers which was six times its normal capacity. This is an excerpt that describes the reason for the overcrowding on the SS Sultana: "The American Civil War had ended just weeks before, and repatriated Union prisoners of war, having endured hellish conditions in Confederate military prisons, were eager to return to their homes in the North."
Since the federal government was paying the steamboat operators for each soldier who was transported, there was widespread corruption by those trying to make a quick buck, and the safety of the boats transporting the soldiers became the least of their concerns. As per reports, this failure to ensure the SS Sultana was safe to operate led to the horrific explosion of three of its four boilers: " In the case of the Sultana, that meant cutting corners on the repair of a leaky boiler and carrying as many as 2,300 people—more than six times the vessel’s rated capacity. When the overtaxed boiler ruptured, hundreds were killed in the initial explosion, and more were trapped when the overloaded decks collapsed."
Even though several vessels joined in the rescue efforts, many of the survivors succumbed to the frigid waters of the Mississippi River while waiting to be rescued.