Born in Laurens District, South Carolina, to John Archer Elmore and Nancy Ann Martin; among his siblings was his half brother Franklin H. Elmore, who served in both U.S. House of Representatives and the U.S. Senate representing South Carolina.
Elmore began a practicing law in New Orleans in 1835, forming a partnership with William W. King.
He served as Attorney General of Louisiana during the governorship of Isaac Johnson from 1846 to 1850.
He was later judge of the Eighth District Court by the appointment of Governor Francis T. Nicholls.
Elmore died of apoplexy at Crowell House in Greencastle, Pennsylvania on October 6, 1890, just a week short of his 78th birthday.