[1] His father was a successful physician, politician and planter who was second cousin to George Washington and held great prominence in the local community.

He graduated from Washington and Lee University in 1820 and moved to Huntsville, Alabama, to practice law with his brother Harry Innes Thornton.

[1] Thornton's strong familial ties encouraged an endeavor into politics fueled by a successful law practice and considerable wealth from the plantation he had developed upon arriving in the state.

[2] Thornton proved to be highly successful and respected in his political office and subsequently dissolved his law practice.

In 1825, he married his first wife, Mary Ann Glover, whose family had already begun to develop lucrative cotton plantations in the area.

[7] Though many had improved their positions through advantageous marriage, it is likely that Thornton and his brother were more prudent in seeking to establish themselves in the booming cotton regions.

[1] The Glovers had been a moderately affluent South Carolina family who, by the time of Thornton's marriage, had acquired vast land and slave holdings.