Born on November 13, 1886, in Milledgeville, Baldwin County, Georgia, Lumpkin moved with his parents to Columbia, South Carolina, in 1898.

[1] There were seven siblings, who by birth order were: Elizabeth (teacher), Hope (clergyman), Alva (politician), Morris (lawyer), Grace (writer), and Katharine (academic).

He was a member of the Conciliation Commission for Advancement of Peace between the United States and Uruguay in 1914.

He was confirmed by the United States Senate on May 22, 1939, and received his commission on July 19, 1939.

[3] Lumpkin was appointed on July 17, 1941, as a Democrat to the United States Senate to fill the vacancy caused by the resignation of United States Senator James F. Byrnes and served from July 22, 1941, until his death in Washington, D.C., on August 1, 1941,[1] following a gastric hemorrhage two days prior.