Arkansas seceded May 6, 1861 and Joined the Confederacy on May 18, 1861. Mail delivery from and to Arkansas during this period continued to be handled by the US Post Office Department. The Confederate Postmaster General Reagan issued a decree on May 1 that the CSA Post Office would begin to handle all mail in the seceded states on June 1, 1861.
Letters mailed from Arkansas on May 6 through May 17 are considered to have been mailed in an Independent state, belonging neither to the United States nor the Confederate States.
Letters mailed from Arkansas on May 18 through May 31 represent letters from a Confederate state but handled by the US Post Office.
The following are covers mailed during this period that have been sold publically in the last 50 years. I would of course like to be notifed of covers not in this list. Please use the email entry on the main page to notify me of any additions.