Thereafter, he was appointed Caddo Parish administrator, a position often called "county judge" in other states. In this position, he was able to exercise his administrative skills and leave political matters to elected parish commissioners.
Hanna defeated outgoing Public Works Commissioner Donald E. Hathaway, a fellow Democrat who later became sheriff of Caddo Parish, to win the position of mayor in the November 1978 general election, often termed the runoff election in Louisiana. The Republican candidate, outgoing Public Utilities Commissioner Billy James Guin, Sr., had been eliminated in the jungle primary held on September 16.
Hanna was well-known for his popular sales slogan "You Canna Ford a Hanna Ford." The company no longer exists.
Hanna was the first Shreveport mayor under the mayor-council home-rule charter, which replaced the former commission form of city government. He was also the first mayor in decades who was not serving in public office at the time of his election. He recruited nationally and secured exceptional people to serve in municipal government. Many noted that Hanna did not seem really interested in "politics". Such an attitude made it appear that he did not like being mayor.
Former Mayor James Creswell Gardner, I (born 1924) served as a city council member in the Hanna administration and helped to chart the new form of government to fruition. Other council members included Charles J. Peatross, a future judge of the Louisiana Court of Appeals; Gregory Tarver, a future member of the Louisiana State Senate; John Scotto, a civil engineer from southwest Shreveport; Hilry Huckaby, first vice-chairman of the council, and the Reverend Herman Farr (1918-2008), a leader of the Shreveport NAACP. Tarver, Huckaby, and Farr were the first African Americans to have served in Shreveport municipal government since Reconstruction.
In his memoirs entitled Jim Gardner and Shreveport, Vol. II, Gardner described Hanna accordingly:
"His self-assurance as a businessman shaped his approach to running city government. He sought proven professionals as department heads, something for which he never received adequate credit. He could never bring himself to 'view with alarm and point with pride' as a political leader must do. And so he never received the credit that he was due. . . .
"In four years, he never initiated a political conversation in my presence. It was just not his thing, and it made his position not as pleasant for him as it could have been. But he always desired to do what he felt was best for Shreveport. And no taint of improperiety ever attached itself to him."
When he ran for mayor, Hanna had a home on Cross Lake, a vacation place in New Mexico, and a private airplane at his disposal. He did not seek reelection as mayor. John Brennan Hussey won a hard-fought campaign against former State Senator Don W. Williamson for the right to succeed Hanna.
Hanna graduated from C.E. Byrd High School in Shreveport in 1947.
James C. Gardner, Jim Gardner and Shreveport, Vol. II, (Shreveport: Ritz Publications, 2006), pp. 224-225