Jefferson County, Arkansas is a county located in the U.S. state of Arkansas in the area known as the Arkansas Delta that extends west of the Mississippi River. Jefferson County consists of five cities, two towns, and 20 townships. It is bisected by the Arkansas River, which was critical to its development and long the chief transportation byway. In 2020, Jefferson County's population was estimated at 67,260. The county seat and largest city is Pine Bluff. The county is included in the Pine Bluff metropolitan statistical area. The county seat and the most populous city is Pine Bluff.

Arkansas County is a county located in the U.S. state of Arkansas. As of the 2020 census, the population was 17,149. Located in the Arkansas Delta, the county has two county seats, DeWitt and Stuttgart.