Short answers, pulled from the story.
The United States Census Bureau includes sixteen states and the District of Columbia within the Southern region. This boundary encompasses over 114 million people as of 2010, representing thirty-seven percent of all U.S. residents at that time.
Human occupation in the southern United States began around 9500 BC with groups now called Paleo-Indians. These hunter-gatherers roamed in bands and hunted megafauna before later cultures like the Archaic period lasted until 1000 BC.
Robert E. Lee led the Confederate Army against attacks on the capital of Richmond during the war. The Confederacy collapsed when Atlanta fell and William T. Sherman marched through Georgia in late 1864 before Lee surrendered his army in April 1865.
White Democrats created state constitutions hostile to industry and business development from the 1890s onward while disenfranchising laws stripped African Americans and poor whites from voter rolls. Between 1910 and 1940 more than 6.5 million African Americans left for Northern and Western cities, and five million more left between 1940 and 1970.
World War II marked dramatic economic change as new industries and military bases developed by the federal government with sixty percent of Army training camps built in the region. Per capita income jumped 140% from 1940 to 1945 compared to 100% elsewhere while Southern income rose from 59% to 65%.