Poinsett County was formed on February 28, 1838, with land taken from Greene (formed 1833), Jackson (formed 1828), St. Francis (formed 1827), and Lawrence Counties (formed 1815).
It was named for Joel Roberts Poinsett, U.S. Secretary of War in President Van Buren's administration. He was also a botanist and horticulturist and introduced a new flower, the poinsettia, into the United States.
County business was initially conducted in the county judge's home until first court was held in Bolivar, upon completion of a courthouse in 1839. County government was moved in 1856 to Harrisburg, a more central locale designated as the new county seat. Poinsett County acquired its current boundaries in the years following this change, as portions were assigned to newly organized counties. The northern portion became Craighead County, and the south portion became Cross County. Sunken lands were added to eastern Poinsett County during this time, including Lepanto, Tyronza and Marked Tree.
The boundaries of Poinsett County have changed dramatically over the years so you will want to search surrounding counties for records when researching your ancestors. Today, adjacent counties are Craighead (north), Mississippi (east), Crittenden (southeast), Cross (south), and Jackson (west).