The development of the Town of Leaside, named for 19th-century farmer and settler William Lea, is historically linked to the Canadian Pacific and Canadian Northern Railways. By 1894, a railway station was established at "Leaside Junction". The Canadian Northern Railway subsequently acquired substantial holdings in the area for the development of a locomotive repair shop and a marshalling yard for its Eastern Lines.
In 1912, the Canadian Northern Railway announced its intention to build a large residential community, commissioning noted Montreal-based landscape architect Frederick Todd to design a model town. The Town of Leaside was incorporated in May 1913, with a population of 43, and land was advertised for sale a month later. Monies from the sale of the land were intended to finance the railway line's maintenance facilities. In the late 1930s, industrial development along Laird Drive - which had become a hub for manufacturers - stimulated residential growth.