Dizengoff became head of the town planning in 1911, a position that he held until 1922. When Tel Aviv was recognized as a city, Dizengoff was elected mayor. He remained in office until his death, apart from a three-year hiatus in 1925-1928. During World War I, the Ottomans drove out a large part of the population and Dizengoff was the liaison between the exiles and the Ottoman authorities. In this po- sition he dealt with aid sent to the exiles of Tel Aviv and received the nickname Reish Galuta. Many committees and associations came into being during Dizengoff's term as mayor. One was the Yerid HaMizrah ('Orient Fair") committee, founded in 1932, which organized itsfirst fair that year. Initially, the fair was held in the south of the city, but after its great success, a fairground with designated buildings was built in north Tel Aviv. Alarge international fair was held in 1934, followed by a second fair two years later. Dizengoff was consequently involved with the development of the city, and en- couraged its rapid expansion -carrying out daily inspections, and paying attention to details such as entertainment. He was always present at the head of the Adloyada, the annual Purim carnival. After his wife's death, he donated his house to the city of Tel Aviv, for use as an art museum, and he influenced many important artists to donate their work to improve the museum.