Swing state

In American politics, the term swing state refers to any state that could reasonably be won by either the Democratic or Republican presidential candidate. 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.

Due to the winner-take-all style of the Electoral College, 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 identifies the states of Colorado, Florida, Iowa, Michigan, Minnesota, Ohio, Nevada, New Hampshire, North Carolina, Pennsylvania, Virginia, and Wisconsin as "perennial" swing states that have regularly seen close contests over the last few presidential campaigns.

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 quite common for a candidate to secure sufficient electoral votes while not having won the national popular vote, such as in the case of the 2016 presidential election. From past electoral results, a Republican candidate can expect to easily win most of the northern mountain states, such as Idaho, Wyoming, the Dakotas, Montana, Utah, Kansas, Oklahoma, and Nebraska, while a Democrat usually takes the New England states, including Vermont, Massachusetts, Rhode Island, and Connecticut.

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