Youngest of a family of 11 children, A.S.J. Carnahan was born January 9, 1897, on a farm near Ellsinore, Missouri. He attended the Crommertown one-room country school near his family's farm home in Carter County, and in 1914, at the age of 17, began teaching in the Crommertown School, a rural school in his home county. After two years teaching at Crommertown and two years at Hogan Hollow, another rural school in Carter County, he taught fourth through eighth grades for one year in Ellsinore.
Mr. Carnahan spent one year in the United States Navy during World War I, serving in an aviation unit stationed in Ireland, and then returned home to finish his formal education and begin a career as Superintendent of Schools in Missouri's hill counties. After completing the last two years of high school at the College High School in Cape Girardeau, Carnahan earned a Bachelor's Degree in Education from Southeast Missouri State Teachers College (now University) in 1926, attending classes mostly during the Spring and Summer terms. In 1932, he received a Master's Degree from the University of Missouri.
The Southeast graduate served as a school administrator in Carter, Reynolds, and Shannon Counties until 1944, when he received the Democratic nomination for Representative in Congress from Missouri's Eighth Congressional District.
He was elected to Congress in November of that year, and served seven terms until his retirement in January 1961.
As a Member of Congress, Mr. Carnahan served on the House Committee on Foreign Affairs, beginning with his first term, and at the time of his retirement was the ranking member of that Committee. For several years, he served as Chairman of the Subcommittee on International Organizations and Movements and the Subcommittee on Africa. He helped write such major legislation as the GI Bill, the Marshall Plan, the Area Development Act, and a revision of the Social Security statutes, was a delegate to the 12th General Assembly of the United Nations in 1957, and served as Congressional Advisor to the U. S. Delegation to the Second International Conference on Peaceful Uses of Atomic Energy in Geneva in 1958.
After leaving office, Carnahan was appointed by President John F. Kennedy to serve as the United States Ambassador to the newly independent African nation of Sierra Leone, and he arrived in that country's' capital on June 8, 1961, and served for two years.
Upon his retirement from public life, Mr. Carnahan returned to his home in Ellsinore, and continued his interest in international service as a member of the Rotary Club of Poplar Bluff. He became Rotary District World Service Chairman, and inaugurated a program to aid in the education of children in Sierra Leone.
He was the recipient of the University's Alumni Merit Award in 1962, in recognition of his long and distinguished career in public service. Mr. Carnahan and his wife, the former Kathel Schupp, were the parents of two children, Robert E. and Melvin E. Carnahan. Mr. Carnahan died March 24, 1968.