TRIVIAL PURSUITS: How Many States Seceded from the Union?

How many states seceded from the Union during the Civil War?
By PS
Eleven, including:

South Carolina – December 20, 1860
Mississippi – January 9, 1861
Florida – January 10, 1861
Alabama – January 11, 1861
Georgia – January 19, 1861
Louisiana – January 26, 1861
Texas – February 1, 1861
Virginia – April 17, 1861*
Arkansas – May 6, 1861*
North Carolina – May 20, 1861*
Tennessee – June 8, 1861*

* These four states seceded after Fort Sumter (April 12, 1861).

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