[23] In 1784, he left the Waxhaws region for Salisbury, North Carolina, where he studied law under attorney Spruce Macay.[24] He completed his training under John Stokes,[25] and was admitted to the North Carolina bar in September 1787.[26] Shortly thereafter, his friend John McNairy helped him get appointed as a prosecuting attorney in the Western District of North Carolina,[27] which would later become the state of Tennessee. While traveling to assume his new position, Jackson stopped in Jonesborough. While there, he bought his first slave, a woman who was around his age.[28] He also fought his first duel, accusing another lawyer, Waightstill Avery, of impugning his character. The duel ended with both men firing in the air.[29]
Jackson began his new career in the frontier town of Nashville in 1788 and quickly moved up in social status.[30] He became a protégé of William Blount, one of the most powerful men in the territory.[31] Jackson was appointed attorney general in 1791 and judge advocate for the militia the following year.[32] He also got involved in land speculation,[33] eventually forming a partnership with fellow lawyer John Overton.