In American politics, the term swing state (or battleground state) refers to any state that could reasonably be won by either the Democratic or Republican presidential candidate by a swing in votes. These states are usually targeted by both major-party campaigns, especially in competitive elections. Meanwhile, the states that regularly lean to a single party are known as safe states, as it is generally assumed that one candidate has a base of support from which they can draw a sufficient share of the electorate without significant investment by their campaign.
Due to the winner-take-all method most states use to determine their presidential electors, candidates often campaign only in competitive states, which is why a select group of states frequently receives a majority of the advertisements and partisan media. The battlegrounds may change in certain election cycles and may be reflected in overall polling, demographics, and the ideological appeal of the nominees.
Election analytics website FiveThirtyEight in 2016 identified the states of Colorado, Florida, Iowa, Michigan, Minnesota, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania, Virginia, and Wisconsin as "perennial" swing states that have regularly seen close contests over the last few presidential campaigns.
In 2020 FiveThirtyEight updated this analysis noting that the electoral map is "undergoing a series of changes," with some states (e.g. Iowa, Michigan, Maine) swinging sharply rightward, and other "Red" states moving leftward by at least 4 points (e.g. Arizona, Georgia, Texas). Likewise, analysis of results of the 2018 midterms indicated that the "battleground states" are changing with Colorado (increasingly Democratic) and Ohio (increasingly Republican) becoming less competitive, and Georgia and Arizona moving into swing state territory.
In American presidential elections, each state is free to decide the method by which its electors to the Electoral College will be chosen. To increase its voting power in the Electoral College system, every state, with the exceptions of Maine and Nebraska, has adopted a winner-take-all system, where the candidate who wins the most popular votes in a state wins all of that state's electoral votes. The expectation was that the candidates would look after the interests of the states with the most electoral votes. However, in practice, most voters tend not to change party allegiance from one election to the next, leading presidential candidates to concentrate their limited time and resources campaigning in those states that they believe they can swing towards them or stop states from swinging away from them, and not to spend time or resources in states they expect to win or lose. Because of the electoral system, the campaigns are less concerned with increasing a candidate's national popular vote, tending instead to concentrate on the popular vote only in those states which will provide the electoral votes it needs to win the election, and it is far from unheard of for a candidate to secure sufficient electoral votes while not having won the national popular vote.
In past electoral results, Republican candidates would have expected to easily win most of the mountain states and Great Plains, such as Idaho, Wyoming, the Dakotas, Montana, Utah, Kansas, Oklahoma, and Nebraska, most of the South, including Alabama, Georgia, Mississippi, Louisiana, Arkansas, Tennessee and South Carolina, as well as Alaska. A Democrat usually takes the Mid-Atlantic states, including New York, New Jersey, Maryland and Delaware, along with New England, particularly Vermont, Massachusetts, Rhode Island, and Connecticut, the West Coast states of California, Oregon and Washington, along with Hawaii.
However, states that consistently vote for one party at the presidential level occasionally elect a governor of the opposite party; this is currently the case in Massachusetts, Maryland, and Vermont, which all have Republican governors, as well as in Louisiana, Kentucky, Kansas, and Montana, which currently have Democratic governors. Even in presidential election years, voters may split presidential and gubernatorial tickets. In 2016, this occurred in Vermont and New Hampshire, which elected Republican governors even as Hillary Clinton won both states, while Montana and West Virginia elected Democratic governors despite also voting for Donald Trump.
In Maine and Nebraska, the apportionment of electoral votes parallels that for Senators and Congressional Representatives. Two electoral votes go to the person who wins a plurality in the state, and a candidate gets one additional electoral vote for each Congressional District in which they receive a plurality. Both of these states have relatively few electoral votes – a total of 4 and 5, respectively. Neither Maine, which is generally considered a Democratic-leaning state, nor Nebraska, typically thought to be safely Republican, would become battlegrounds in the event of a close national race. Despite their rules, only once has each state 'split' its electoral votes – in 2008, when Nebraska gave 4 votes to Republican John McCain, and one to Democrat Barack Obama; and in 2016, when one of Maine's congressional districts was won by Donald Trump, and the other district and the state itself were won by Hillary Clinton.
States where the election has a close result become less meaningful in landslide elections. Instead, states which vote similarly to the national vote proportions are more likely to appear as the closest states. For example, the states in the 1984 election with the tightest results were Minnesota and Massachusetts. A campaign strategy centered on them, however, would not have been meaningful in the Electoral College, as Democratic nominee Walter Mondale required victories in many more states than Massachusetts, Republican Ronald Reagan still would have won by a large margin. Instead, the tipping-point state that year was Michigan, as it gave Reagan the decisive electoral vote. The difference in Michigan was nineteen percentage points, quite similar to Reagan's national margin of eighteen percent. Michigan would have been more relevant to the election results had the election been closer.
Similarly, Barack Obama's narrow victory in Indiana in the 2008 election inaccurately portrays its status as a battleground. Obama lost Indiana by more than ten percentage points in the closer 2012 election, but triumphed anyway as Indiana's electoral votes were not directly needed for a coalition of 270 votes ; the same scenario was with Missouri, where John McCain narrowly won by 4,000 votes in the 2008 United States presidential election, but was won by Mitt Romney by nearly 10 points in 2012 United States presidential election, indicating its GOP trends. Other lightly-Republican leaning states such as North Carolina and Arizona were more plausible Democratic pick-ups in 2012. In 2012, the states of North Carolina, Florida, Ohio, and Virginia were decided by a margin of less than five percent. However, none of them were considered the tipping-point state, as Romney would not have been able to defeat Obama even if he had emerged victorious in all of them. Interestingly, Virginia was most in-step with the rest of the country. Virginians voted for Obama by just under 4 points, almost the exact same as the nation. Had the election come out closer, Romney's path to victory would probably have involved also winning Wisconsin, Nevada, New Hampshire, or Iowa, as these states had comparable margins to Colorado, and had been battlegrounds during the election.
As many mathematical analysts have noted, however, the state voting in a fashion most similar to that of the nation as a whole is not necessarily the tipping-point. For example, if a candidate wins only a few states but does so by a wide margin, while the other candidate's victories are much closer, the popular vote would likely favor the former. However, although the vast majority of the states leaned to the latter candidate in comparison to the entire country, many of them would end up having voted for the loser in greater numbers than did the tipping-point state. The presidential election in 2016 was a notable example, as it featured one of the largest historical disparities between the Electoral College and popular vote. Additionally, this "split" in votes was much larger in both directions than in previous elections, such as the 2000 election. In that election, Vice President Al Gore won the popular vote by less than 1 percent, while incoming president George W. Bush won the Electoral College by only 4 votes. In contrast, 2016 Democratic nominee Hillary Clinton won the popular vote by over 2 percentage points. This meant that Donald Trump would have picked up New Hampshire, Nevada, and Minnesota if the popular vote had been tied, assuming a uniform shift among the battleground states. On the other hand, Clinton would have had to win the popular vote by at least 3 points in order to win the Electoral College, as Trump, the Republican nominee, won the tipping-point state of Wisconsin by less than 1 percent.
Swing states have generally changed over time. For instance, the swing states of Ohio, Connecticut, Indiana, New Jersey and New York were key to the outcome of the 1888 election. Likewise, Illinois and Texas were key to the outcome of the 1960 election, Florida and New Hampshire were key in deciding the 2000 election, and Ohio was important during the 2004 election. Ohio has gained its reputation as a regular swing state after 1980, and last voted against the winner in 1960. In fact, only two people have won the presidential election without winning Ohio since 1900: Franklin D. Roosevelt and John F. Kennedy. If current trends from the 2012 and 2016 elections continue, the closest results in 2020 will occur in Arizona, Florida, Maine, Michigan, Minnesota, Nebraska's second congressional district, Nevada, New Hampshire, North Carolina, Pennsylvania, and Wisconsin, with Florida, Michigan, Pennsylvania, and Wisconsin constituting the "Big Four" most likely to decide the electoral college. Other potential swing states in 2020 include states designated as "tipping point" states by FiveThirtyEight 
Determining swing states
Presidential campaigns and pundits seek to keep track of the shifting electoral landscape. While swing states in past elections can be determined simply by looking at how close the vote was in each state, determining states likely to be swing states in future elections requires estimation and projection based on previous election results, opinion polling, political trends, recent developments since the previous election, and any strengths or weaknesses of the particular candidate involved. The swing-state "map" transforms between each election cycle, depending on the candidates and their policies, sometimes dramatically and sometimes subtly. For example, in the 2016 election, Hillary Clinton overperformed in educated, suburban states such as Virginia and Colorado compared to past Democratic candidates, while Donald J. Trump performed over standard Republican expectations in the Upper Midwest, such as Michigan, Ohio, and Pennsylvania. In addition, gradual shifts can occur within states due to changes in demography, geography, or population patterns. For example, many currently Republican states, like Arkansas, Missouri, Tennessee, and West Virginia, had been battlegrounds as recently as 2004.
According to a pre-election 2016 analysis, the thirteen most competitive states were Wisconsin, Pennsylvania, New Hampshire, Minnesota, Arizona, Georgia, Virginia, Florida, Michigan, Nevada, Colorado, North Carolina, and Maine. Nebraska's 2nd congressional district is also considered competitive. However, this projection was not specific to any particular election cycle, and assumed similar levels of support for both parties.
The electoral college encourages political campaigners to focus most of their efforts on courting swing states. States in which polling shows no clear favorite are usually targeted at a higher rate with campaign visits, television advertising, get out the vote efforts by party organizers and debates. According to Katrina vanden Heuvel, a journalist for 'The Nation', "four out of five" voters in the national election are "absolutely ignored".
Since most states use a winner-takes-all arrangement, in which the candidate with the most votes in that state receives all of the state's electoral votes, there is a clear incentive to focus almost exclusively on only a few undecided states. In contrast, many states with large populations such as California, Texas, and New York, have in recent elections been considered "safe" for a particular party, and therefore not a priority for campaign visits and money. Meanwhile, twelve of the thirteen smallest states are thought of as safe for either party – only New Hampshire is regularly a swing state, according to critic George Edwards. Additionally, campaigns stopped mounting nationwide electoral efforts in the last few months near/at the ends of the blowout 2008 election, but rather targeted only a handful of battlegrounds.
Swing states by results
This is a chart of swing states using the methodology of Nate Silver for determining tipping point states, but including the other states in close contention in recent elections, ranked by margin of victory. In this method, states and DC are ordered by margin of victory, then tabulating which state(s) were required to get to 270+ electoral votes in margin order. The tipping point state, and the next 10 states with close margins on each side, are shown as the swing states in retrospect. Note that this takes into account inherent electoral college advantages; for example, Michigan was the closest state in 2016 by end result, and Nevada was the closest state to the national popular vote result, but the tipping points that most mattered for assembling a 270 electoral vote coalition were Wisconsin and Pennsylvania.
|2016 election||Margin||2012 election||Margin||2008 election||Margin||2004 election||Margin||2000 election||Margin|
|New Hampshire||0.37%D||New Hampshire||5.58%D||New Hampshire||9.61%D||Iowa||0.67%R||Wisconsin||0.22%D|
|Michigan||0.23%R||Pennsylvania||5.39%D||Iowa||9.53%D||New Mexico||0.79%R||New Mexico||0.06%D|
|Wisconsin[note 1]||0.77%R||Virginia||3.87%D||Virginia||6.30%D||Nevada||2.59%R||New Hampshire||1.27%R|
|North Carolina||3.66%R||North Carolina||2.04%R||Indiana||1.03%D||Missouri||7.20%R||Nevada||3.55%R|
- The 2016 election had two possible tipping point states, depending on how they are calculated. If faithless electors are ignored, then Wisconsin was the tipping point in 2016; if they are included, then Donald Trump's loss of 2 EV's from faithless electors means that Pennsylvania is also required for his coalition to reach 270 electoral votes, while Hillary Clinton's loss of 5 EV's doesn't change that Wisconsin remains the tipping point for her potential coalition.
- "Larry J. Sabato's Crystal Ball » The Electoral College: The Only Thing That Matters". centerforpolitics.org. Retrieved January 27, 2017.
- Beachler, Donald W.; Bergbower, Matthew L.; Cooper, Chris; Damore, David F.; Dooren, Bas Van; Foreman, Sean D.; Gill, Rebecca; Hendriks, Henriët; Hoffmann, Donna (October 29, 2015). Schultz, David; Hecht, Stacey Hunter (eds.). Presidential Swing States: Why Only Ten Matter. Lexington Books. ISBN 9780739195246.
- "The Odds Of An Electoral College-Popular Vote Split Are Increasing". FiveThirtyEight. November 1, 2016. Retrieved November 6, 2016.
- Silver, Nate (April 27, 2012). "Arizona Is (Probably) Not a Swing State". The New York Times. Retrieved June 6, 2013.
- Silver, Nate (November 8, 2012). "As Nation and Parties Change, Republicans Are at an Electoral College Disadvantage". Retrieved June 6, 2013.
- Silver, Nate (September 20, 2016). "2016 Senate Forecast | FiveThirtyEight". FiveThirtyEight. Retrieved November 6, 2016.
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- Chang, Alvin. "Trump will be the 4th president to win the Electoral College after getting fewer votes than his opponent". Vox. Retrieved January 27, 2017.
- "Clinton's popular vote lead surpasses 2 million". USA TODAY. Retrieved January 27, 2017.
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- Malone, Clare (July 18, 2016). "The End Of A Republican Party". FiveThirtyEight. Retrieved January 27, 2017.
- "1888 Overview" p.4, HarpWeek.
- "Daley Remembered as Last of the Big-City Bosses", David Rosenbaum, New York Times, April 21, 2005.
- Trolling the Campuses for Swing-State Votes, Julie Salamon, "The New York Times", October 2, 2004
- Game Theory for Swingers, Jordan Ellenberg, "Slate.com", October 25, 2004
- Weaver, Dustin (November 24, 2017). "How Dem insiders rank the 2020 contenders". TheHill. Retrieved January 13, 2018.
- Balz, Dan (August 31, 2019). "The 2020 electoral map could be the smallest in years. Here's why". Washington Post. Retrieved January 5, 2019.
- "Battleground States Poll - June 21, 2004". Wall Street Journal. June 21, 2004. Retrieved July 5, 2017.
- "Larry J. Sabato's Crystal Ball » The Electoral College: The Only Thing That Matters". centerforpolitics.org. Retrieved May 21, 2016.
- "Larry J. Sabato's Crystal Ball » The Electoral College: Pennsylvania Moves Toward Clinton". centerforpolitics.org. Retrieved September 30, 2015.
- Katrina vanden Heuvel (November 7, 2012). "It's Time to End the Electoral College". The Nation. Retrieved November 8, 2012.
Electoral college defenders offer a range of arguments, from the openly anti-democratic (direct election equals mob rule), to the nostalgic (we’ve always done it this way), to the opportunistic (your little state will get ignored! More vote-counting means more controversies! The Electoral College protects hurricane victims!). But none of those arguments overcome this one: One person, one vote.
- Edwards III, George C. (2011). Why the Electoral College is Bad for America (Second ed.). New Haven and London: Yale University Press. pp. 1, 37, 61, 176–7, 193–4. ISBN 978-0-300-16649-1.
- Silver, Nate (February 6, 2017). "Donald Trump Had A Superior Electoral College Strategy". FiveThirtyEight. Retrieved February 26, 2019.
- The Critical 2012 Swing States
- Battleground States 2008 via the Washington Post
- Swing State Ohio Documentary
- Swing State feature documentary project
- Guide to the 2004 swing states from Slate
- Battleground states from Democracy in Action site hosted by George Washington University
- How close were Presidential Elections? Influential States - Michael Sheppard
- The Bush campaign memo detailing its look at the swing states (PDF file)