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. President James Buchanan appointed him superintendent of the New Orleans Mint and was retained in that position when the mint came under the control of the Confederate government in 1861. He was later judge of the Eighth District Court by the appointment of Governor Francis T. Nicholls.
Elmore married twice, first to Mary Ann Morrison on July 28, 1840. Following her death, he married Julia Minor on January 2, 1851 in Ascension Parish. He had children by both wives.
- The New York Herald, Obituary of William Augustus Elmore, October 7, 1890.
- The Daily Picayune, Obituary of William Augustus Elmore, October 7, 1890.
Isaac Trimble Preston
| Attorney General of Louisiana