Gershon Agronski served as mayor between the years 1955-1959.
Born in 1893 to Yehuda and Sheindl, daughter of Rabbi Mirenberg of Romny, in Mena, in the Chernihiv province of Ukraine, which was then part of the Russian Empire. He received traditional Jewish education at a "Cheder", and in 1906 immigrated with his family to Philadelphia in the United States, where he completed his high school studies and academic studies at Temple University. Even in his youth he was already involved in Zionist activity, and even initiated the founding of a Zionist youth club and served as its secretary. In 1915, he represented the Jews of Philadelphia as an envoy to an all-American Zionist convention in Boston. In 1917 he moved to reside in New York and served as editor of the Zionist Organization's journal "Das Yiddishe Volk" ("The Jewish People"). In 1918, during the First World War, he enlisted in the American battalion of the Jewish Legions and fought alongside the British on the soil of Eretz Israel. In the spring of 1920, he was released from his military service, decided to stay in Eretz Israel and settled in Jerusalem.
In that year, he managed the Press Bureau of the World Zionist Organization. Between the years 1921 and 1924, he managed the news agency YTA (Yiddishe Telegraph Agentur) in New York. In 1924, he resumed management of the World Zionist Organization's Press Bureau, while serving as a correspondent in Jerusalem for important newspapers around the world, such as the Times and the Daily Telegraph.
On December 1st, 1932, he founded the English-language newspaper Palestine Post in Jerusalem and became its editor. Under Mandatory rule, the Palestine Post adopted a position of support of the struggle to establish a national home for the Jewish people in Eretz Israel and employed an overt and decisive line against the limitations imposed by the British rule on the immigration of Jews to Eretz Israel. In 1950, the newspaper changed its name to "The Jerusalem Post".
On June 8th, 1949,  he entered his position as Head of the Intelligence (Publicity) Services, which was moved from the Ministry of the Interior to the Prime Minister's office,  and served in the position until March 1st, 1951, when he resumed his journalistic work in his newspaper. 
On September 7th, 1955, Agron was elected as Mayor of Jerusalem,  and served in this position until his death. In August of 1956, he was saved from an attempt to oust him thanks to Rahamim Kalanter, who left his faction, "HaPoel HaMizrachi", that acted to have Agron removed from office, and became a supporter of Agron. In return, Kalanter was appointed as deputy mayor in charge of religious and sanitation affairs. This act created the term "Kalanterism".