Swing states, also known as battleground states, are states that could “swing” to either Democratic or Republican candidates depending on the election. Because of their potential to be won by either candidate, political parties often spend a disproportionate amount of time and campaign resources on winning these states.
While there is no universal definition of what identifies a swing state, they are characterized by having small vote margins and that different political parties win over time. Since 1992, 30 states have voted for the candidate of the opposite party from the previous election at least once. And 26 states were won by less than three points in any presidential election since 1992.
The states that voted for current Democratic President Joe Biden in 2020 and former Republican president Donald Trump in 2016 and are often highlighted as swing states. These states include Arizona, Georgia, Michigan, Pennsylvania, and Wisconsin. All five of these states have governorship elections in the 2022 midterms. Four of them—Arizona, Georgia, Pennsylvania, and Wisconsin—have Senate seats up for election this year as well.
Tight margins in races also indicate that a state could have been won by either party. In 2020, seven states were won by a margin of three percentage points or less. These states included the five above states, in addition to North Carolina and Nevada.
Due to the small vote margin in 2020, these states may be more likely to have tighter statewide races in the upcoming midterm elections.
Political realignment from presidential election to presidential election—such as from Trump to Biden—can be one way to identify swing states. Years where a president is up for re-election tend to have fewer states that change parties, but since 1992, every presidential election has had at least a few states switch party affiliations.
Of the past eight presidential elections, the 1992 election had the highest number of states that switched political parties. With 22 states that flipped from the previous election, it is often cited as a year of political realignment, where Bill Clinton’s defeat of George H.W. Bush turned many states that historically voted Republican (including California, Colorado, Maryland, among others) into states that reliably voted for Democrats for the next decade.
There hasn’t been a presidential election since 1992 with that many states voting for a different political party’s presidential candidate.
But many states have had close presidential elections in the last 40 years. Over the past eight presidential elections, 26 states were won by less than a three-point margin in at least one election. This includes Florida and Nevada, which had tight margins in five of the last eight elections.
These swing states have also shifted over time. New Mexico and Iowa, for instance, were swing states under this definition in 2000 and 2004 but not since that time. Arizona and Georgia have cycled in and out of being swing states over the past two decades.
Since the 1988 election, 20 states and Washington, DC have voted for the same party in every presidential election. Of these 20 states, only three — Minnesota in 2016 and 2000, Oregon in 2000, and Washington in 1988 — have ever had close elections.
Seven states and Washington, DC have consistently voted for the Democratic presidential candidate since 1988, and 13 states have consistently voted for the Republican presidential candidate. While there was some speculation that Texas was becoming a swing state in 2020, the margin between the Republican and Democratic vote was still 5.5 percentage points.
An additional eight states switched party alignment from 1988 to 1992 but have voted for the same party every election since.
Swing states also tend to be better predictors of the overall election winner. While Florida was famously the deciding state in the 2000 election, several others have also been reliable bellwethers of overall election results. Over the past nine elections, Nevada and Ohio have been predictive of the overall election result eight times.
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