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Southwestern Ontario

Southwestern Ontario
Secondary region
Coordinates: 43°30′N 81°00′W / 43.500°N 81.000°W / 43.500; -81.000
CountryCanada Canada
ProvinceOntario Ontario
 • Total36,797.54 km2 (14,207.61 sq mi)
 • Total2,583,544
 • Density70/km2 (180/sq mi)
Time zoneUTC−5 (EST)
 • Summer (DST)UTC−4 (EDT)
Postal code prefixes
Area code(s)519, 226, 548, 905, 289, 365

Southwestern Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario. It occupies most of the Ontario Peninsula bounded by Lake Huron, including Georgian Bay, to the north and northwest; the St. Clair River, Lake St. Clair, and Detroit River, to the west; and Lake Erie to the south. To the east, on land, Southwestern Ontario is bounded by Central Ontario and the Golden Horseshoe. The region had a population of 2,583,544 in 2016. It is sometimes further divided into "Midwestern Ontario" covering the eastern half of the area and the heart of Southwestern Ontario encompassing the western half of the region.


The Government of Ontario also classifies municipalities along the eastern side of Southwestern Ontario near the Grand River, including Wellington County (containing Guelph), the Region of Waterloo (containing Kitchener, Waterloo, and Cambridge), and Brant County (containing Brantford), as part the "Greater Golden Horseshoe" region that surrounds western Lake Ontario.[1] Some non-profit organizations, government bodies, and news organizations also classify a larger swath of the eastern side of Southwestern Ontario (the area from Huron County, Bruce County, and Grey County in the north, southward through Dufferin County, Wellington County, the Region of Waterloo, Perth County, and Oxford County, and sometimes south to Brant County and Norfolk County on Lake Erie) as being "Midwestern Ontario."[2][3][4][5][6][7][8][9][10][11][excessive citations] This thereby places only the counties southwest of this in their definition of Southwestern Ontario,[12] although in some cases Perth County is also grouped in Southwestern Ontario.[citation needed]

London, Ontario in June 2009.


Archaeological findings from the Princess Point Complex suggest that indigenous peoples grew maize in the region as early as 260 CE. Iroquoians are recognizable from 500 CE, and by 900 CE longhouse villages began appearing near modern-day Brantford.[13]

Europeans settlement began in the early 18th century, when it was part of the Royal Province of New France. One of the oldest continuous settlements in the region is Windsor, which originated as a southerly extension of the settlement of Fort Detroit in 1701. With the transfer of New France to British control in 1763, the region was part of the British Province of Quebec, 1774 to 1791; the Province of Upper Canada, 1791 to 1841; and the Canada West division of the Province of United Canada, 1841 to Confederation in 1867, when United Canada was formally partitioned into the provinces of Ontario and Quebec.

During the 19th century and early 20th century, the largest city in Southwestern Ontario was Windsor; however, as both cities grew, Windsor was outpaced by the faster growth of London, and passed the mantle of regional anchor to that city in the 1960s. Late in the 20th century the Kitchener–Cambridge–Waterloo metropolitan area became the most populous metropolitan area in southwestern Ontario surpassing the London-St. Thomas metropolitan area, and serves as the anchor of Midwestern Ontario.

Southwestern Ontario is a prosperous agricultural region whose chief crops are tobacco, sweet corn, soybean, winter wheat, canola, and tomatoes.[14] Additionally, Southwestern Ontario has developed a significant concentration of commercial greenhouses, predominantly centred in the town of Leamington, where tomatoes, peppers, cucumbers, flowers, and cannabis are grown. It is the largest concentration of commercial greenhouses in North America. Dairy and beef farming, breeding and training of standardbred horses and wine growing and production are also important industries. Its climate is among the mildest in Canada. Although brief periods of winter can be severe, summers are hot and humid with a longer growing season than in most of the country.

A large section of Southwestern Ontario was part of the Talbot Settlement, and the region has benefited from the settlement’s facilitation of agriculture and of trade in general. Its economy is heavily tied in with that of the midwestern United States, in particular the border state of Michigan. Auto manufacturing and parts, agriculture and hi-tech industries are key components of the region’s economy. The region also provides important transportation routes for commercial trucking, railway and tanker shipping from Detroit-Windsor and Port Huron, Michigan-Sarnia linking Canada with major markets in the eastern and midwestern United States.

Today the largest cities in Southwestern Ontario, in order of population (2016), are: London, Kitchener, Windsor, Guelph, Cambridge, Waterloo, Brantford, Sarnia, Woodstock, St. Thomas, Leamington, and Stratford. Chatham is also a major population centre, but is not an independent municipality and is part of Chatham-Kent.

The largest cities in Southwestern Ontario's estimated 2023 population, (Also including the City of Chatham): London (410,003), Kitchener (254,449), Windsor (226,321), Guelph (152,963), Cambridge (134,495), Waterloo (114,335), Brantford (103,147), Sarnia (70,527), Chatham (47,441), Woodstock (45,755), St. Thomas (40,359), Stratford (32,269), and Leamington (26,502).


Southwestern Ontario is located within the Mixedwood Plains Ecozone (as classified by Environment and Climate Change Canada, which largely consists of glacial till plains underlain by limestone bedrock. The vast majority of Southwestern Ontario maintains a relatively flat geography with rolling hills, with the exception of areas near the Niagara Escarpment in Bruce and Grey Counties, where exposed limestone cliff faces can be seen along the shores of Georgian Bay. Sandier soils are generally located near Lake Erie, resulting in the creation of many sandspit peninsulas, including Point Pelee in Essex County, Pointe aux Pins (Rondeau) in Chatham-Kent, and Long Point in Norfolk County. Pelee Island, the southernmost populated area in Canada, is located south of Point Pelee in Lake Erie.

Southwestern Ontario was originally covered by vast forests prior to agricultural development in the region. Two forest regions are located in Southwestern Ontario; Carolinian forest, located predominantly along Lake Erie and the southern tip of Lake Huron, and Great Lakes-St. Lawrence forest, located around Lake Huron and Georgian Bay.[15] A very small percentage of forest coverage areas remain in the region due to extensive agricultural development and urbanization, but conservation efforts are underway to preserve and/or preserve these forests. Three major federally protected areas, Point Pelee National Park, Bruce Peninsula National Park, and Long Point National Wildlife Area, are located in Southwestern Ontario.

The Carolinian forest zone is Canada's smallest forest zone, but it is home to a very high biodiversity of species due to it being one of the warmest regions in the country. Over 500 rare and/or endangered species are located in this region.[16]

Weather and climate

Like other parts of southern Canada, the region brings warm or hot summers with normal thunderstorm occurrences. Some of these storms are severe, with damaging winds, hail and tornadoes all possible during peak season, May through September. The most likely areas for these kinds of weather events is within the Windsor - London corridor and north up to about Huron County. Winters are cold with less snowfall in the south towards Essex County and higher amounts north towards Bruce County. London receives approximately 30% more snowfall than Windsor, owing to its relative position to Lake Huron and the resulting snowbelt in Bruce and Middlesex Counties.

Under the Köppen climate classification, much of this area has a humid continental climate (Köppen Dfa/Dfb borderline).



The vast majority of the primary vehicular traffic network in Southwestern Ontario is served mainly by the controlled-access 400-series highways. Highway 401, the main highway in the network, starts in Windsor and runs northeast to Waterloo Region, where it continues northeast through the Golden Horseshoe. Highway 402, another major highway, runs east from the United States border with Michigan in Sarnia to London, where it connects with Highway 401 in southern London. Highway 403 connects with Highway 401 in Woodstock and runs east toward Brantford, where it continues toward Hamilton and the Greater Toronto Area. Additional major provincial highways in the region include Highway 3, Highway 4, Highway 6, Highway 7, Highway 8, Highway 9, Highway 21, Highway 24, Highway 40, and Highway 85. Highway 3 has two sections that are built out as partially controlled-access expressways in Essex County and Elgin County/St. Thomas. Highway 6 is built as a partially controlled-access expressway through Guelph and Wellington County. Highways 7, 8, and 85 are built as fully controlled-access expressways throughout Waterloo Region. Highway 40 is built as a partially controlled-access expressway through Sarnia and Lambton County. All other provincial highways largely consist of two-lane rural highways.

Major road infrastructure projects are currently in planning or underway in Southwestern Ontario, as the region is seeing high levels of population growth and business investment. The Gordie Howe International Bridge is the most prominent project in the region and is being built to serve as a direct freeway-to-freeway connection between Highway 401 in Windsor and Interstate 75 in Detroit. As of 2024, additional ongoing and planned major road projects in the region include the widening of Highway 401 between Tilbury and London, widening of Highway 401 through Waterloo Region, widening of Highway 3 between Essex and Leamington, freeway conversion of Highway 3 in St. Thomas and Elgin County, freeway conversion of Highway 6 in Guelph, construction of a new alignment of Highway 7 between Waterloo Region and Guelph, and widening of Highway 40 in Sarnia.


The region is also serviced by major ports in Goderich on Lake Huron, Windsor on Lake Erie and just to the east Hamilton on Lake Ontario which is major destination for regionally produced grain.


Southwestern Ontario is home to three major airports; Region of Waterloo International Airport, London International Airport, and Windsor International Airport, in addition to a number of minor airports in various smaller communities. These main airports predominantly offer limited international flights (mainly to vacation destinations such as the United States, Mexico, and the Caribbean) on a seasonal basis, in addition to some select all-season routes to other Canadian cities, and offer frequent connecting flights to Toronto Pearson International Airport, usually via Air Canada.


The accent in the region, Southwestern Ontario English, is distinct from the rest of Ontario.

Administrative divisions

Blue Water Bridge, Sarnia, Ontario

Single-tier municipalities

Separated municipalities

Regional municipalities



  1. ^ Transportation Profile
  2. ^ " - Midwestern Ontario News - Your Local News Network". 2021-06-16. Retrieved 2021-06-17.
  3. ^ "Midwestern Ontario District: |". Archived from the original on 2018-02-07.
  4. ^ "Ontario Newsroom". Retrieved 2021-06-17.
  5. ^ "A2001.100 - Kitchener - Waterloo Record / Map of / Midwestern Ontario, 1951. | Wellington County Museum & Archives".
  6. ^ "Ontario Hockey League – Official Site of the Ontario Hockey League". Retrieved 2021-06-17.
  7. ^ "WELCOME TO THE OFFICIAL HOME OF THE MID". 2005-07-21. Archived from the original on 2005-07-21. Retrieved 2021-06-17.
  8. ^ "Bereaved Families of Ontario – Midwest Region". Retrieved 2021-06-17.
  9. ^ "University of Toronto Libraries". Retrieved 2021-06-17.
  10. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2020-11-30. Retrieved 2019-10-07.((cite web)): CS1 maint: archived copy as title (link)
  11. ^ "Midwestern Branch". Retrieved 2021-06-17.
  12. ^ "The Official Tourism Website of Ontario".
  13. ^ Warrick, Gary (2000). "The Precontact Iroquoian Occupation of Southern Ontario". Journal of World Prehistory. Springer. 14 (4): 415–466. doi:10.1023/A:1011137725917. ISSN 0892-7537. JSTOR 25801165. S2CID 163183815. Retrieved 2022-02-14.
  14. ^ Zong Jia, Chen (15 June 2022). "Ontario is an agricultural powerhouse that leads in many farming categories". Statistics Canada. Retrieved June 23, 2023.
  15. ^ "One tree at a time: Canada's forests". Retrieved 2024-02-11.
  16. ^ "Carolinian Canada | Carolinian Canada". Retrieved 2024-02-11.
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Southwestern Ontario
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