Electoral district boundaries are adjusted to reflect population changes after each
decennial census through a process formally known as
redistribution. Depending on the significance of a boundary change, an electoral district's name may change as well. Any adjustment of electoral district boundaries is official as of the date the changes are legislated, but is not put into actual effect until the first subsequent election. Thus, an electoral district may officially cease to exist, but will continue to be represented
status quo in the House of Commons until the next election is called. This, for example, gives new riding associations time to organize, and prevents the confusion that would result from changing elected MPs' electoral district assignments in the middle of a Parliament. On some occasions (e.g.,
Timiskaming—French River,
Toronto—Danforth), a riding's name may be changed without a boundary adjustment. This usually happens when it is determined at a later date that the existing name is not sufficiently representative of the district's geographic boundaries. This is the only circumstance in which a sitting MP's riding name may change between elections.
Redistribution Occurrences At
Canadian Confederation, the boundaries were defined by the
British North America Act, 1867 (renamed in 1982 as the
Constitution Act, 1867). Seats allocations to provinces based on the immediate prior
decennial census, and consequently the electoral boundaries, were updated in 1872, 1882, 1892, 1903, 1914, 1924, 1933, 1947 and 1952 by statutes titled
Representation Act, [YEAR]. Seats were further added to provide representation for new provinces at the elections held in 1874 (for Prince Edward Island), 1887 (For the Northwest Territories), 1908 (for Alberta and Saskatchewan) and 1949 (for Newfoundland). The redistribution process was significantly revised by the
Electoral Boundaries Readjustment Act passed in November 1964. Non partisan electoral boundaries commissions were to be established to revise the electoral district boundaries in each province. The descriptions of the electoral districts resulting from the process are included in a
Representation Order prepared by the
Chief Electoral Officer, given legal effect by proclamation of the
Governor-in-Council and published in the
Gazette. Due to the lateness of the passage of the legislation and the longer period required for the work of the commissions, the population data from the 1961 census was not reflected until the proclamation of the
1966 Representation Order and did not take effect until the
1968 federal election. Electoral boundaries were update by
Representation Orders issued in 1966, 1976, 1987, 1996, 2003,
Seats allocation on principle of representation by population The electoral districts for the
first federal election in 1867 were prescribed on the principle of representation by population. Quebec was allocated 65 to retain the 65 seats
Canada East in the
Parliament of the Province of Canada prior to confederation. Seats were allocated to other three provinces by dividing the average population of Quebec's 65 electoral districts to determine the number of seats for other provinces. The
British North America Act also specified that distribution and boundary reviews should occur after each 10 year census. The formula currently in effect for seat allocations to provinces was adopted in 2022. It starts by calculating an electoral quotient, based on the average of the growth rate of the provinces since the time of the last redistribution, the previous redistribution's electoral quotient is then multiplied by this average, and then the population of each individual province is divided by this electoral quotient then rounded up to determine the number of seats to which the province is officially entitled. Additionally, one seat is automatically allocated to each of Canada's three territories.
Deviations from representation by population Two special rules are prescribed in the in effect to maintain the number of seats allocated to provinces with declining shares of the national population. The
Senatorial Clause, incorporated into the
Constitution Act, 1867 (as section 51A) in 1915, prescribed that a province's number of seats in the House of Commons can never be lower than the province's representation in the
Senate. The
Grandfather Clause, first enacted in the
Representation Act, 1985, guarantees each province no fewer seats than it had at a particular point in history. The 1985 legislation was designed to limit rapid increase of the total number of MPs expected under the previous formular. To mitigate the likely corresponding decrease, a special provision was included to set each province's baseline number to their seat count in
33rd Parliament that was in session in 1985. The baseline numbers were further updated to the provinces' seat counts in the
43rd parliament (in session
2019 - 2021) by the government of Prime Minister
Justin Trudeau in 2022 through the passing of the
Preserving Provincial Representation in the House of Commons Act . The
Representation Rule, enacted in 2012 by the
Fair Representation Act, further prescribes that no province that had a higher share of seats than its population share in the last redistribution can have its share of seats drop below its population share. In response to the ensuing opposition in Quebec, three new seats were allotted to Quebec as well. The measure was not pass before the
2011 election but was reintroduced and adopted in December 2011 and was put in effect through the 2012 redistribution process. A province may be allocated extra seats over its base entitlement to ensure that these rules are met. In 2022, for example,
Prince Edward Island would have only received two seats according to the electoral quotient, but through the senatorial clause the province maintained its four seats in the Commons, equal to its four senators.
New Brunswick similarly maintained ten seats under the senatorial clause.
Quebec would have 71 seats by the electoral quotient alone, but through the historic seats provision the province maintained the 78 seats it had in the 43rd Parliament.
Saskatchewan,
Manitoba,
Nova Scotia and
Newfoundland and Labrador also maintained seats under the historic seats provision. In practice, the process results in most provinces maintaining the same number of seats from one redistribution to the next, due to the senatorial and historic seats provision. From 1985 onwards, only
Ontario,
Alberta and
British Columbia, traditionally the country's three fastest-growing provinces, had gained seats in a redistribution. All other provinces still held the same number of seats that they held in 1985, and were thus already protected from losing any seats by the other clauses. The
2012 redistribution, which added three new seats in Quebec under the newly added representation rule, was the first and so far only time since 1985 that any of the other seven provinces had gained new seats. Some sources incorrectly state that a special provision guaranteeing a certain number of seats to Quebec is also applied. While such a provision was proposed in the failed
Charlottetown Accord, no such rule currently exists—Quebec's seat allotment in the House of Commons is in fact governed by the same adjustment clauses as all other provinces, and not by any provisions unique to Quebec alone. However, such provisions have existed at various times in the past. From 1867 to 1946 Quebec was allocated 65 seats, with the other provinces allocated seats based on their size relative to Quebec. The "amalgam formula" of 1976 set the number of Quebec seats to 75, which was to be increased by 4 after each decennial census. Other "large" provinces (over 2.5 million) would be assigned seats based on their relative population to Quebec. The amalgam formula was applied only once, based on the 1971 census. After the 1981 census it was realized that adding an additional four seats to Quebec every ten years would rapidly inflate the size of the House of Commons, so that formula was abandoned in favour of the 1985
Representation Act.
Boundary review of federal electoral districts When the province's final seat allotment is determined, an independent election boundaries commission in each province reviews the existing boundaries and proposes adjustments. Public input is then sought, which may then lead to changes in the final boundary proposal. For instance, the proposed boundaries may not accurately reflect a community's historical, political or economic relationship with its surrounding region; the community would thus advise the boundary commission that it wished to be included in a different electoral district. For example, in the 2003 boundary adjustment, the boundary commission in Ontario originally proposed dividing the city of
Greater Sudbury into three districts. The urban core would have remained largely unchanged as
Sudbury, while communities west of the central city would have been merged with
Algoma—Manitoulin to form the new riding of Greater Sudbury—Manitoulin, and those east and north of the central city would have been merged with
Timiskaming to create the riding of Timiskaming—Greater Sudbury. Due to the region's economic and transportation patterns, however, "Timiskaming—Greater Sudbury" was particularly opposed by its potential residents — voters in Sudbury were concerned about the weakening of their representation if the city were divided into one city-based riding and two large rural ones rather than two city-based ridings, while the
Timiskaming District is much more strongly aligned with and connected to
North Bay, to which it has a direct highway link, than to Sudbury. In a deputation to the boundary commission, Sudbury's
deputy mayor Ron Dupuis stated that "An electoral district must be more than a mere conglomeration of arbitrary and random groups of individuals. Districts should, as much as possible, be cohesive units with common interests related to representation. This makes a representative's job of articulating the interests of his or her constituency much easier." although due to concerns around balancing the
Northern Ontario region's population against its geographic size, the commission announced in 2013 that it would retain the existing electoral districts again. Similarly, opposition arose in
Toronto during the 2012 redistribution process, especially to a proposal which would have divided the
Church and Wellesley neighbourhood, the city's primary
gay village, between the existing riding of
Toronto Centre and a new riding of Mount Pleasant along the length of
Wellesley Street. In the final report, the northern boundary of Toronto Centre was shifted north to Charles Street. Once the final report is produced, it is then submitted to Parliament, MPs may offer objections to the boundaries, but the boundary commissions are not compelled to make any changes as a result of the objections. ==Boundary adjustment for provincial and territorial electoral districts==