Louisiana's 42nd governor was born in Winnfield, La. on August 8, 1882. He attended Winn Parish public schools, along with the Long brothers, Huey P. and Earl K. "He was of a genial nature and made friends easily, and held the confidence of the public," remarks Miriam Reeves in The Governors of Louisiana of Allen's young years.
Allen continued his education at Springfield Normal School and Business College in Missouri and Trinity University in Texas, and was teaching school as early as 1898 in Winn Parish and elsewhere in Louisiana and Texas. He went onto work as an assistant registrar at Trinity University, a sawmill owner and manager back in Winnfield, a farmer and a railroad builder and by 1918, an oil and mercantile businessman.
Allen was involved in Democratic politics and first entered public office as Winn Parish's assessor in 1916. Four years later, he served as the parish's police jury clerk until his election to the La. State Senate in 1928 – he was firmly on Huey P. Long's political coattails by this point and defeated an anti-Long incumbent, Henry E. Hardtner of La Salle Parish. Allen became the floor leader of Long's bloc in the Senate, and the governor appointed him as chairman of the Louisiana Highway Commission in 1928. The La. Supreme Court ruled in 1930 that Allen's dual legislative-executive role violated the state constitution.
When Long turned his attentions and ambitions to the U.S. Senate, he tapped Allen as his gubernatorial successor. Allen ran on Long's "Complete the Work" ticket and won the governor's mansion unopposed in 1932.
Allen was reliable as a Long lieutenant, going so far as to call his own term the "Long-Allen administration." When the Kingfish needed something done in Louisiana, he picked up his phone in Washington, D.C. and called Allen. Earl Long once joked that a leaf once blew into Allen's office window and, thinking it a bill from the Kingfish, signed it into law.
Louisiana, like the rest of the nation, was in the depths of the Great Depression in the early 30's, and Allen became a critical point of contact for local governments in Louisiana, searching for federal funds to prop up their budgets and restore civic services. Allen also worked through federal New Deal programs to kick off public work efforts. "During his tenure, the public school system was expanded, highway and bridge construction was advanced, a tick elimination program was accomplished, and Louisiana State University and state hospitals were modernized," reads an account of Allen's record by the National Governors Association. But when Allen joined Long in criticizing the Roosevelt administration, Allen, Long and Louisiana could do little but watch as public works funding was cut off.
When Long was assassinated in 1935, Allen picked up the reins of Long's political machine and soon announced his bid for the vacant U.S. Senate seat. He won the Democratic primary by some 200,000 votes and seemed poised for a move to Washington. But he died of a cerebral hemorrhage in the Governor's Mansion on January 28, 1936.