East and West Florida were transferred to the United States from Spanish control in 1821.
And on "July 21, 1821, Andrew Jackson established Escambia and St. Johns counties in the areas known as West and East Florida. St. Johns County encompassed all areas east of the Suwanee River," according to St. Johns County government. Following the 1821 transfer of Florida and the formation of Escambia and St. Johns counties, "In 1822, the provisional government was replaced by a territorial council, which consisted of the governor and 13 presidential appointees. The Territorial Council reaffirmed many of Jackson's 1821 ordinances under the Acts of the Legislative Council.
"That same year, the two existing counties, Escambia and St. Johns, were further divided into Escambia, Jackson, Duval and St. Johns counties. Duval was carved out of the boundaries of St. Johns County."