In politics, a “clean sweep” occurs in an election when a candidate or party achieves an overwhelming or complete victory, winning in all or almost all districts or precincts.
A related term is “landslide” or “wipeout” victory.
In open democracies that are deeply partisan, as in the United States, clean sweeps on a national level are uncommon.
Even locally, true clean sweeps, in which one candidate or party receives the vast majority of the vote, are rare.
In the history of presidential elections, there has never been a true clean sweep, but in 1972 Richard Nixon won 49 of 50 states, and in 1984 Ronald Reagan lost only Minnesota and Washington, D.C.
Notably, in many countries where corruption is built into the political system, clean sweeps are much more common, as in Belarus and Iraq, in which Saddam Hussein would commonly boast of “clean sweeps,” often winning 99% of the vote.
There are examples of legitimate clean sweeps occurring in nationwide elections, when there is overwhelming rejection of a country’s political class, as in the 2018 national elections of Barbados, in which the opposition party won every seat in the country’s parliament.
Sometimes, if an opposition party boycotts an election, a clean sweep can happen by default, as was the case in the Jamaican elections of 1983, in which the Conservative JLP party “won all 60 House seats and formed a one-party legislature.”
One of the most storied true clean sweeps in electoral history took place in 1987 in New Brunswick, Canada, as described by the CBC:
Liberal Frank McKenna had expected to win, but he never expected this. His Liberal party has won every single seat in the New Brunswick legislature. A clean sweep like this has only ever happened once before, in P.E.I. in 1935. ‘I did not anticipate it, and I guess it really hasn’t sunk in yet, as to what it means,’ says a stunned McKenna in this CBC news clip. McKenna must now get to work to figure out how to run a government with no opposition.
Of course, with a clean sweep usually comes a mandate from voters as well.
Not limited to politics, the term “clean sweep” is also used in sports, as in Major League Baseball, where there have been 21 World Series sweeps, in which a team has won the series without losing a game.