A landslide victory is an electoral victory in a political system, when a change in people's views on political matters results in one candidate or party receiving an overwhelming majority of the votes or seats in the elected body, thus all but utterly eliminating the opponents. Part of the reason for a landslide victory is sometimes a bandwagon effect, as a significant number of people may decide to vote for the party which is in the lead in the pre-election opinion polls, whereas they wouldn't have voted the same way if it seemed unpopular. The term is borrowed from geology, where a landslide takes almost everything with it on its way, creating a change in the landscape.
For some people, a landslide victory is synonymous to an overwhelming victory, but there is no consensus on how wide a margin is necessary for an overwhelming or lopsided victory is necessary to justify a landslide.  In this usage, there is no inherent shift from one side to the other, no change in the landscape.
A map of the vote by province in 1940 shows the scale of the Liberals' landslide victory.
A map of the vote by province in 1984 shows the scale of the Progressive Conservatives' landslide victory.
In a Canadian federal election, a landslide victory occurs when a political party gains a significant majority of the House of Commons of Canada.
Landslide victories may also occur during provincial elections, and territorial elections in Yukon. Landslide victories are not possible for territorial elections in the Northwest Territories, and Nunavut, as its members are elected without reference to political parties, operating as a consensus government.
The following Canadian federal elections resulted in landslide victories:
- 1874 - The Liberals won 133 seats while the Conservatives won just 73 seats.
- 1878 - The Conservatives won 137 seats while the Liberals won just 69 seats.
- 1882 - The Conservatives won 139 seats while the Liberals won just 71 seats.
- 1900 - The Liberals won 132 seats while the Conservatives won just 81.
- 1904 - The Liberals won 139 seats while the Conservatives won just 75.
- 1908 - The Liberals won 133 seats while the Conservatives won just 85.
- 1911 - The Conservatives won 133 seats while the Liberals won just 86.
- 1917 - The Conservatives won 153 seats while the Liberals won just 82.
- 1930 - The Conservatives won 137 seats while the Liberals won just 91.
- 1935 - The Liberals won 171 seats while the Conservatives won just 39.
- 1940 - The Liberals won 178 seats while the Progressive Conservatives won just 39.
- 1949 - The Liberals won 190 seats while the Progressive Conservatives won just 41.
- 1953 - The Liberals won 171 seats while the Progressive Conservatives won just 51.
- 1958 - The Progressive Conservatives won 208 seats while the Liberals won just 48.
- 1968 - The Liberals won 155 seats while the Progressive Conservatives won just 72.
- 1984 - The Progressive Conservatives won 211 seats while the Liberals won just 40.
- 1993 - The Liberals won 177 seats while the Bloc Quebecois, which ran only in Québec, won 54. The ruling Progressive Conservatives dropped from 154 to 2.
- 2015 - The Liberals led by Justin Trudeau won 184 seats, defeating Conservative Prime Minister Stephen Harper, who only won 99 seats.
- 1968 legislative election: the Gaullist party wins 3/4 of all seats.
- 1981 legislative elections: the PS wins 266 out of 481
- 1993: the liberal-conservative coalition RPR-UDF wins 84% of the seats in parliament.
- 2002 - Jacques Chirac wins the presidential election with 82.1% of the popular vote. His party also has won 357 seats out of 577.
Because of Germany's multi-party mixed-member proportional representation system, it is extremely difficult for any one party to gain a majority in the Bundestag. Thus, a landslide election occurs when a party gains close to a majority and has a large margin over its main opponent in the popular vote and are very rare.
- 1953: The CDU/CSU received 45.2% of the popular vote and 249 seats (six shy of a majority) while the SPD received just 28.8% of the popular vote and 162 seats.
- 1957: The CDU/CSU received 50.2% of the popular vote and 277 seats (a majority of 17) while the SPD received just 31.8% of the popular vote and 181 seats.
- 2013: The CDU/CSU received 41.5% of the popular vote and 311 seats (five shy of a majority) while the SPD received just 25.7% of the popular vote and 193 seats.
Before 1993, New Zealand used the traditional first-past-the-post system as in the U.K. to determine representation in its Parliament. Thus, landslide elections at that time were defined in an identical fashion, i.e. where one party got an overwhelming majority of the seats. Since 1993, New Zealand has used the mixed member proportional system as in Germany, making landslides much less likely.
Ramon Magsaysay (light green)'s 1953 landslide victory.
In 1941, the Nacionalista Party won the presidency, vice presidency, all seats in Senate and all but 3 seats in the House of Representatives. This was the biggest landslide in Philippine history. The legislators won't serve until 1945 though, due to World War II.
Starting in 1987, the Philippines evolved into a multi-party system, and coupled with the introduction of party-list elections in 1998, no party was able to win a landslide, much less a majority of seats, in the House of Representatives since then. This has also meant that no presidential and vice presidential election winner won a majority of votes, although in 1998, the winners were described in having landslide victories, despite winning less than a majority of votes, due to large winning margins. Senatorial landslides are more possible though in midterm elections, as voters are usually presented with two distinct choices.
Presidential and vice presidential elections
In the Philippines, while there are presidential tickets, the positions of president and vice president are elected separately.
- 1935 election - Manuel L. Quezon won with 68% of the vote. His running mate, Sergio Osmeña, won with 86% of the vote. Their second placers had 18% and 8% of the vote, respectively.
- 1941 election - Manuel L. Quezon won with 82% of the vote. His running mate, Sergio Osmeña, won with 92% of the vote. Their opponents had 18% and 8% of the vote, respectively. This was the biggest landslide in an election where major opposition parties participated.
- 1953 election - Ramon Magsaysay won with 69% of the vote. His running mate, Carlos P. Garcia, won with 63% of the vote. Their opponents had 31% and 37% of the vote, respectively.
- 1981 election - Ferdinand Marcos won with 89% of the vote, and won on every province. Major opposition parties boycotted this election. This is the largest landslide in history.
- 1998 election - Joseph Estrada won with 40% of the vote. His main opponent, Jose de Venecia, received just 16%, or a margin of 24%. De Venecia's running mate, Gloria Macapagal Arroyo, won with almost 50% of the vote. Her main opponent, Estrada's running mate Edgardo Angara, received just 22%, or a margin of about 28%.
House of Representatives
- 2011: local, regional and national elections were all landslide wins for the then-in opposition Mariano Rajoy's PP, winning the national election by a 16 percentage point margin to then-ruling PSOE.
In UK General Elections, a landslide victory involves a large swing from one party to another as well as one party winning a large majority in parliament. Landslide victories have usually occurred after a long period of government from one particular party and a change in the popular mood.
Notable landslide election results:
- 1906 General Election - Known as the 'Liberal Landslide', Henry Campbell-Bannerman led his Liberal Party to victory over Arthur Balfour's Conservative Party who lost more than half their seats, including his own seat in Manchester East, as a result of the large national swing to the Liberal Party (The 5.4% swing from the Conservatives to Liberals was at the time the highest ever achieved). The Liberal Party won 397 seats (an increase of 214) while the Conservative Party were left with 156 seats (a decrease of 246).
- 1945 General Election - Clement Attlee led his Labour Party to victory over Winston Churchill's Conservative Party, a 12.0% swing from the Conservatives to Labour. Labour won 393 seats (an increase of 239) while the Conservative Party were left with 197 (a decrease of 190).
- 1983 General Election - Margaret Thatcher won her second term in office with a landslide victory for the Conservatives gaining an overall majority of 144 by winning 397 seats (a increase of 38 seats) on 42.4% of the national vote and forcing her main opponent Michael Foot to resign after Labour won 209 seats.
- 1997 General Election - Tony Blair's Labour Party won 418 seats (an increase of 145) and gained an overall majority of 179 while the Conservative Party won 165 seats (a decrease of 178). The swing from the Conservatives to Labour was 10.2% and was the second biggest general election victory of the 20th Century after 1931.
- 2019 General Election - Boris Johnson led the Conservative Party to its largest majority since 1987, winning a total of 365 seats (an increase of 48) and left the Labour Party, who were led by Jeremy Corbyn, with 202 seats (a decrease of 60, their worst result since 1935). The election led to 54 Labour seats changing to Conservative predominantly in the Midlands and Northern England - some of which had been held by Labour since the first half of the 20th century.
The map of the Electoral College in 1972
shows the scale of Richard Nixon
's landslide victory.
The map of the Electoral College in 1984
shows the scale of Ronald Reagan
's landslide victory.
A landslide victory in U.S. Presidential elections occurs when a candidate has an overwhelming majority in the Electoral College.