Arkansas County Courthouse is located at 101 Court Square, De Witt Arkansas 82042; phone: 870‑946‑4321.
Arkansas County was first formed on December 31, 1813, through the passage of an act by the legislature of the state of Missouri, of which this county was a part at the time. However, the first organized civil government within the present boundaries of the state had actually been established as early as 1804 — after the completion of the Louisiana Purchase by the United States Government — with the appointment of James B. Maney as the civil Governor to preside at Arkansas Post, a trading center on the north bank of the Arkansas River and the only such organized settlement within the state at that early date. The initial boundaries of Arkansas County included approximately ninety per cent of the modern land area of the entire state, with Arkansas Post as its county seat. Many counties were subsequently carved out of that enormous area, eventually resulting in the establishment of its current boundaries by 1871.