Initially, Arkansas Territory included all of what is now Eastern Oklahoma. When Post Offices were established in the Indian Nations, they were administered from Arkansas, and most had "ARK" in their town marks. This relationship continued through the Civil War, and town marks containing "ARK" are know well into the 1870s.
Separate pages are used to show Covers From before July 1, 1851, covers from the period July 1, 1851 to May 31, 1861, Confederate and Union occupation Usages through 1865, and then usages post war. These can be reached from the pull down menu, or click on the links below. Each page then has sub-pages with ranges of post office cover scans.
Post War covers