Jackson was born on June 24, 1820, in Athens, Georgia. His father, Henry Jackson, brother of James, 1757-1806, was a native of Devonshire, England. He migrated to America in the latter years of the eighteenth century and settled in Georgia. After graduation (M. D. , 1802) from the medical department of the University of Pennsylvania, he became secretary to William H. Crawford, then minister to France, served as chargé d'affaires after Crawford's return, and then began a long service as professor of mathematics in the University of Georgia. He married Martha Jacqueline Rootes of Fredericksburg, Virginia, and Henry Rootes Jackson was their son.