Leaside takes its name from William Lea and the Lea family, who settled there in the early years of the nineteenth century. The area first developed as farmland along with Toronto through the nineteenth century. It was incorporated as a town in 1913. In 1967 it was amalgamated with the township of East York to form the borough of East York. In 1998 it became part of the city of Toronto.

In the 1870s, the Ontario and Quebec Railway Company purchased a few acres of land on the south-east corner of William Lea's property to run its railway across. The Ontario and Quebec Railway Company encountered financial difficulties in 1884, and leased part of its railway, including the section of track running through Leaside, to the Canadian Pacific Railway for 999 years. The Canadian Pacific Railway decided to establish a maintenance stop and a sliding by-pass on the railway on the land purchased from William Lea, which was attractive because it was uniformly flat. The station was completed in September 1884 and named "Leaside" in honour of William Lea. In 1892 a junction was built in the Leaside area, and a railway line was constructed south along the Don towards Union StationLeaside.

In 1912, William Mackenzie and Donald Mann, the owners of the Canadian Northern Railway hired planner Frederick Todd to plan development for a community to be built around a maintenance yard for their railway. Mackenzie and Todd founded the York Land Company to purchase land for such a town. The company purchased over 1,000 acres (4.0 km2) most of the third concession and some land north of Eglinton Avenue. [9]The purchased lands extended from the railway tracks in the south to three farms north of Eglinton Avenue, from Leslie Street in the east to Bayview Avenue in the west. The town of Leaside was planned by Todd for the company, which put its name to many of the local streets; Laird Drive, Hanna Road and Wicksteed Avenue all bear the name of Canadian Northern Railway company executives. The new community was planned with commercial areas, residential areas and a town centre west of Laird Drive, and space was laid out east of Laird Drive for industrial development. The goal of the company was to create Leaside as a new upper class residential area of Toronto, the "New Rosedale".

The Town of Leaside was officially incorporated on April 23, 1913. The population of Leaside was 43 individuals.

In 1914 the industrial area that had been set aside east of Laird Drive received its first tenant. Canada Wire and Cable began construction of a factory for production of 9.2 inch shells for World War I. In addition to the new factory, Canada Wire and Cable moved their other Toronto production plants to the same location to increase efficiency. Canada Wire and Cable also created the subsidiary company Leaside Munitions Company to oversee shell production. Soon after construction began on a federal government owned airstrip, named Leaside Aerodrome. The York Land Company leased about 220 acres (0.9 km2) to the government for the airfield, between Wicksteed Avenue and Eglinton Avenue.  On May 21, 1917 construction began on the airfield. At the close of the war, there were accommodations for around 1000 military personal.

Leaside: a growing Toronto suburb

After the war, the strip became the site of Canada's first delivery of airmail on June 18, 1918 when pilot Brian Peck delivered 120 letters from Montreal.

Leaside's growth slowed after World War I, with its primary industry being war industry. However, at this time Leaside stood on the edge of Toronto and was increasingly an appealing place for investment. Investors from Baltimore bought property for the construction of a race track. They formed the Thorncliffe Park Racing and Breeding Association Ltd. to operate the track.

The Leaside Viaduct was completed on October 29, 1927 providing easy connection between east Toronto and Leaside. This led to the rapid growth of Leaside at the time, and in the future. The impassibility of the Don River valley had previously made it difficult for people employed in Toronto to reside in Leaside. The same month, an underpass on Millwood Road was opened through the valley.

In 1945 at the end of World War II the population of Leaside stood at 9800. In 1949, Leaside's population had grown to 14 826.

The last horse race at Thorncliffe Park was run on June 23, 1952. Investors from Toronto bought the racetrack that year.

The rapid growth of Thorncliffe in the 1950s necessitated the construction of a second north-south bridge across the Don Valley. In 1955, Leaside's population had grown to 16 779. The Leaside town council approved a second bridge. Construction was completely on September 7, 1960 with the bridge opened by Leslie Frost. The bridge was named the Charles Hiscott Bridge in honour of Leaside's mayor at the time.


Leaside lies on the Iroquois Plain. The actions of the glacial Lake Iroquois made the Leaside area into a flat plateau, surrounded on three sides by deep river valleys.


The largest recreation centre in Leaside is Leaside Memorial Community Gardens which includes an indoor swimming pool, an ice rink, a curling rink and a large auditorium, and is currently under construction and expanding.

Serena Gundy Park is located in the north-east corner of Leaside. The parkland was donated to Leaside in 1960 by the estate of James H. Gundy. The park covers 62.6 acres which are generally in a natural state. The park is used for picnicking and hiking in the summer and cross country skiing in the winter.

Trace Manes Park is located in south Leaside. The park is home to the Leaside Tennis club and sports six tennis courts. Other facilities in the park include a playground, a baseball diamond and an outdoor ice rink in winter.

Howard Talbot park in south-west Leaside features two baseball diamonds. Additionally it features a "splash pad", a water playground for young children.


Northlea Elementary and Middle School is located on the site of the old Divadale Estate on Rumsey Road north of Eglinton Avenue. It was opened in 1944 and had 15 classrooms. In 1991-93 the school underwent extensive renovations and the school now educates over 800 students. The renovation provided additional classroom space to the school as well as a new library and a second gymnasium. The school is operated by the Toronto District School Board. Northlea is a dual track school offering regular English programs from Junior Kindergarten to Grade 8, and French Immersion programs from Senior Kindergarten to Grade 8.

Bessborough Elementary and Middle School, located on the same road as the high school: Leaside High School in South Leaside has offered a great deal of education to those living in the older part of Leaside. St. Anselm Catholic School, also located on Bessborough Drive, opened in 1939 and presently has an enrollment of 340 students from Junior Kindergarten to Grade 8. Leaside High School began on the top floor of Rolph Rd. School in 1945. The "new" high school opened in September 1948 and welcomed back local students who had been attending Lawrence Park and Jarvis Collegiate.

Rolph Road Elementary School, an elementary school for junior kindergarten to grade 6, is the other elementary school in the neighbourhood. Located on Rolph Road, it is in South Leaside and is a feeder school to Bessborough.