About 1836 Humphreys moved to Hernando, Mississippi, where he worked in banking for the remainder of his life.
As a child, he moved with his family to Kentucky in 1789, part of a westward migration across the Appalachians after the American Revolutionary War.
He served as a justice of the Supreme Court of Tennessee from 1807 to 1809, and a judge of the State judicial circuit from 1809 to 1813.
Afterward, he was a founder of the Nashville chapter of the Ku Klux Klan, which worked to maintain white supremacy over freedmen and their allies.
Morton reportedly initiated noted Confederate general Nathan Bedford Forrest into the KKK.