On March 11, 1861, the Confederate Constitution of seven state signatories – South Carolina, Mississippi, Florida, Alabama, Georgia, Louisiana, and Texas – replaced the February 7 Provisional Confederate States Constitution with one stating in its preamble a desire for a "permanent federal government". Four additional slave-holding states – Virginia, Arkansas, Tennessee, and North Carolina – declared their secession and joined the Confederacy following a call by U.S. President Abraham Lincoln for troops from each state to recapture Sumter and other seized federal properties in the South. Missouri and Kentucky were represented by partisan factions from those states, while the legitimate governments of those two states retained formal adherence to the Union. Also fighting for the Confederacy were two of the "Five Civilized Tribes" – the Chocktaw and the Chickasaw – located in Indian Territory and a new, but uncontrolled, Confederate Territory of Arizona. Efforts by certain factions in Maryland to secede were halted by federal imposition of martial law; Delaware, though of divided loyalty, did not attempt it. A Unionist government in western parts of Virginia organized the new state of West Virginia, which was admitted to the Union during the war on June 20, 1863.

Confederate control over its claimed territory and population in congressional districts steadily shrank from 73% to 34% during the course of the Civil War due to the Union's successful overland campaigns, its control of the inland waterways into the South, and its blockade of the southern coast.[7] With the Emancipation Proclamation on January 1, 1863, the Union made abolition of slavery a war goal (in addition to reunion). As Union forces moved southward, large numbers of plantation slaves were freed. Many joined the Union lines, enrolling in service as soldiers, teamsters and laborers. The most notable advance was Sherman's "March to the Sea" in late 1864. Much of the Confederacy's infrastructure was destroyed, including telegraphs, railroads and bridges. Plantations in the path of Sherman's forces were severely damaged. Internal movement became increasingly difficult for Southerners, weakening the economy and limiting army mobility.

These losses created an insurmountable disadvantage in men, materiel, and finance. Public support for Confederate President Jefferson Davis's administration eroded over time due to repeated military reverses, economic hardships, and allegations of autocratic government. After four years of campaigning, Richmond was captured by Union forces in April 1865. Shortly afterward, Confederate General Robert E. Lee surrendered to Union General Ulysses S. Grant, effectively signalling the collapse of the Confederacy. President Davis was captured on May 10, 1865, and jailed in preparation for a treason trial that was ultimately never held.[8]

Post-war history
The U.S. government began a decade-long process known as Reconstruction which attempted to resolve the political and constitutional issues of the Civil War. The priorities were: to guarantee that Confederate nationalism and slavery were ended, to ratify and enforce the Thirteenth Amendment which outlawed slavery; the Fourteenth which guaranteed dual U.S. and state citizenship to all native-born residents, regardless of race; and the Fifteenth, which guaranteed the right of freedmen to vote.

By 1877, the Compromise of 1877 ended Reconstruction in the former Confederate states. Federal troops were withdrawn from the South, where conservative white Southern Democrats had already regained political control of state governments, often through extreme violence and fraud to suppress black voting. Confederate veterans had been temporarily disenfranchised by Reconstruction policy. The prewar South had many rich areas; the war left the entire region economically devastated by military action, ruined infrastructure, and exhausted resources. Continuing to be dependent on an agricultural economy and resisting investment in infrastructure, the region remained dominated by the planter elite into the 20th century. After a brief period in which a Republican-Populist coalition took power in several southern states in the late 19th century, the Democratic-dominated legislatures worked to secure their control by passing new constitutions and amendments at the turn of the 20th century that disenfranchised most blacks and many poor whites. This exclusion of blacks from the political system, and great weakening of the Republican Party, was generally maintained until after passage of the Voting Rights Act of 1965. The Solid South of the early 20th century was built on white Democratic control of politics. The region did not achieve national levels of prosperity until long after World War II.[9]