 He was instrumental in establishing the School Board Liaison Committee; led a successful fight to keep the Canadian Pacific Railway tracks off the banks of the Bow River; developed Nose Hill and Confederation parks; helped achieve "International" Airport status for Calgary; established the Airport Authority.Leslie was elected mayor in 1965; he was the first native Calgarian to be elected mayor.During his tenure, major low-cost housing schemes were undertaken in several areas of the city, including Urban Renewal efforts; the Palliser Square project was completed and the transformation of Prince's Island into one of the city's beauty spots was begun.