He served as a navigator in the United States Air Force during World War II from 1943 to 1945 and received the air force medal with an oak leaf cluster.
He served as a 1st lieutenant with the United States Air Force Reserve from 1946 to 1951.
[5] Mifflin became a close friend of Ted Williams while working at the Sporting News and is credited with convincing Williams to stay in baseball longer in order to improve his baseball statistics before retirement.
He was elected to the Pennsylvania House of Representatives for Delaware County in 1962 and was reelected in 1964 and 1966.
[5] In 1968 Mifflin was elected to the newly created Pennsylvania House of Representatives, District 161 and was reelected in 1970.