John Austin Gronouski was born in Dunbar, Wisconsin, on October 26, 1919. Gronouski attended St. Peter's School in Oshkosh, Wisconsin and then studied at Oshkosh Teachers College. He received a B.A. in 1942 from the University of Wisconsin.

After graduation, he joined the Army Air Corps and served as a navigator with the Eighth Air Force. Gronouski was discharged in October 1945, returning to school to earn his M.A. from the University of Wisconsin in 1947. He took various lecturing and research positions from 1948 to 1953.

In 1955, Gronouski earned his Ph.

D. from the University of Wisconsin, and continued to teach and conduct research until 1959, when he was appointed research director of the Wisconsin Department of Taxation. Gronouski was also named executive director of Revenue Survey Commission that same year. In 1960, he was made Wisconsin state commissioner of taxation.

Gronouski took over the slot of Postmaster General from J. Edward Day on September 30, 1963 and held that position into the Johnson administration, resigning on November 2, 1965. As Postmaster General, Gronouski added the use of the zip code, instituted a vertically improved mail system of delivery, proposed to do away with airmail postage, and reclassified first class mail as a priority class. Gronouski also served as U.S. Ambassador to Poland from 1965 through 1968. John A. Gronouski died on January 7, 1996.