Henry Blackwell was born and raised in the Tri-Cities region. His father worked for the East Tennessee and Western North Carolina Railroad (ET&WNC), and, as a consequence, the young Blackwell early developed a fondness for the railroad. He graduated from the University of Tennessee with an engineering degree. He served in the United States Army's transportation corps in England and France during World War II. After the war Blackwell remained in the army reserves as the head of a transportation unit headquartered in Johnson City. The unit was reactivated in August 1950 after the June 25th North Korean invasion of South Korea precipitated the Korean conflict. Blackwell reported for duty on September 9, 1950. Subsequently he was sent to Korea where he remained until shortly after the Panmunjom armistice of July 7, 1953. After returning from Korea Blackwell entered into the trucking business with his brother. This venture lasted until 1958 when Blackwell took a position with the state of Tennessee working in manpower and labor-related jobs. Eventually, he became upper East Tennessee's director for the Comprehensive Employment and Training Act (CETA) program.