The Civil War was primarily about slave-holding states retaining the rights to hold and profit from the work of African slave labor. Saying the Civil War was about "States' Rights" ignores historical facts and the specific reasons cited within written slave state Declarations or Ordinances of Secession. Talking about the "Lost Cause" ignores the suffering of those held in bondage as well as the approximate 1.5 million combined casualties (Figure from the American Battlefield Trust; https://www.battlefields.org/learn/articles/civil-war-casualties ). 

The political, financial, commercial, and other ramifications of the agrarian nature of cash crops (cotton, tobacco, sugarcane, rice, soybeans, wheat, etc) North primarily manufacturing, but also benefited financial from cash crops grown by the South. South's primary trading partner was Great Brittan. Great Brittan purchased much of it's cotton from the South in return for manufactured goods.

From 1776 through 1860, pro-slavery states argued for continued utilization of slave labor; expansion of slavery to land by the fledgling United States through purchase, military action, or expansion; allowance of slavery in new states admitted to the Union; and, increased representation of slave-holding states in congress. 

Because ratification of the Declaration of Independence required unanimity, the paragraph in Thomas Jefferson's original draft regarding the slave trade was removed. To get the Constitution passed and ratified, the Constitution included specific passages allowing: (1) slave populations to be apportioned as three fifths of all other persons when determining the number of Representatives each slave state received in Congress [Article 1, Section 2]; (2) migration or Importation of persons by any of the States existing (at the time the Constitution is approved) until 1808 [Article 1, Section 9]; and (3) return of runaway slaves to their "owners" [Article 4, Section 2].

Multiple attempts were made politically to maintain balance between the agrarian slave-holding states and the manufacturing-based northern states. During periods of national expansion, slave and non-slave states were added to the United States in such a way as to maintain balance of the number of Senators in Congress.

Lincoln was not anti-slavery as much as he was against expansion of slavery to new territories and any new State added to the republic. However, not expanding slavery into new territories or newly admitted states mean that slave-holding states would have exponentially less power in Congress. As an example of the slave-state decreasing political power, Lincoln was elected president with less than 40% of the vote and no votes from pro-slavery states. The election of Lincoln as president was one of the primary reasons cited in Declarations and Ordinances of Secession. 

By 1860, slaves were the single most valuable commodity in the fledgling United States at an estimated $3.5 billion or $140.8 billion in 2026 (Per online CPI Inflation Calculator - https://www.in2013dollars.com/us/inflation/1860?amount=3500000000  where $100 in 1860 = $4,023.52 in 2026). Without slaves to work the fields, slave-states lost their greatest financial asset.

 

Two sources were used to locate the State "Ordinances of Secession" or "Declarations of Causes for Secession":

Yale Law School: Lillian Goldman Law Library - The Avalon Project: Documents in Law, History and Diplomacy

© 2008 Lillian Goldman Law Library, 127 Wall Street, New Haven, CT 06511.

and,

American Battlefield Trust - Works to preserve and restore America's hallowed battlegrounds and educates the public about what happened there and why it matters. 

 

Additional detail was found via History.com

 

Confederate State "Ordinances of Secession" / "Declaration of Causes"

Documents & Laws Affecting Extension of Slavery in the United States

Nothing happens in a vacuum. Before the Confederacy fired on Fort Sumter during April 1861, slavery had been a contentious issue between slave and free states since Thomas Jefferson wrote his original draft of the Declaration of Independence. The slavery issue was not addressed in the Declaration of Independence because unanimous consent was required for passage.

However, from 1787 through 1854, either the permission, safeguarding, or prohibition of slavery were written into major legislation. 

Below are links to discussions within this Section about how Congress and lawmakers carefully addressed slavery to maintain a fragile peace between free and slave states, first to establish the United States and then to prevent the Country from dissolving.

The Civil War became inevitable after the Supreme Court's problematic decision in the "Dred Scott" slave-freedom case in 1857. 

Some Confederate States even referenced several of the below laws within their "Declaration of Causes of Secession".

               Description /Link