Whether the state was ever out of the Union is a matter of opinion, and not a position supported by the Supreme Court. See Texas v. White (74 US 700).
It seems odd that each state had to be individually readmitted to the Union then, doesn't it?
Below is a list of the 11 states that seceded from the Union
during the American Civil War, along with the date of secession
and when they were readmitted.
State Seceded
from UnionReadmitted
to Union1. South Carolina Dec. 20, 1860 July 9, 1868 2. Mississippi Jan. 9, 1861 Feb. 23, 1870 3. Florida Jan. 10, 1861 June 25, 1868 4. Alabama Jan. 11, 1861 July 13, 1868 5. Georgia Jan. 19, 1861 July 15, 1870 6. Louisiana Jan. 26, 1861 July 9, 1868 7. Texas March 2, 1861 March 30, 1870 8. Virginia April 17, 1861 Jan. 26, 1870 9. Arkansas May 6, 1861 June 22, 1868 10. North Carolina May 20, 1861 July 4, 1868 11. Tennessee June 8, 1861 July 24, 1866
In actual fact, it was. Otherwise, why were hte Feds fighting it.