Explainer: Red or blue, this is how the ‘swing states’ work in US elections

The 2024 US presidential election will be decided by over 186.5 million American voters, yet the final outcome will likely hinge on just a small fraction of voters in a few key states.

Out of 50 states, only seven are truly competitive this year, with the rest strongly aligned with either Democrats or Republicans, according to current polling data.

These are called the swing states – or battleground states. The term refers to states that can "swing" toward either the Democratic or Republican candidates, depending on voter trends, campaign strategies, and key issues in a particular election.

The stakes are high because the US election is decided not by popular vote but through the Electoral College, where each state’s electoral votes are based on population.

What is the Electoral College?

The Electoral College is the system used to determine the winner of the presidential election.

Each state gets a set number of electoral votes based on population, and the candidate who wins a majority of the 538 electoral votes – which must be at least 270 – wins the presidency.

What is meant by ‘swing’ states?

Swing or battleground states could vote for either party, making them crucial for winning the presidency.

In 2024, key swing states include Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania, and Wisconsin.

Which states will decide the 2024 election?

The critical battleground states are Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania, and Wisconsin. These states have historically been closely contested, and their voters are crucial to determining the final result.

How close is the race?

The 2024 race appears even tighter than in 2020. Back then, a shift of just 43,000 votes in three key states, representing less than a third of a percentage point nationwide, would have been enough for Donald Trump to secure reelection instead of Joe Biden.

Here is a look at the battleground states:

Georgia

2020: Joe Biden won by 10,000 votes

When Joe Biden narrowly won Georgia in 2020, he became the first Democrat to carry the state since 1992, making it a key target for falsified claims of election fraud alleged by Donald Trump and his allies.

However, multiple audits and recounts, including a full hand recount, confirmed Biden’s victory. Courts, both in Georgia and across the US, rejected numerous lawsuits challenging the results due to a lack of credible evidence.

Nevada

2020: Joe Biden won by 34,000 votes

Nevada has leaned Democratic in recent years but with narrow margins. Biden won by just over 2 points in 2020.

About 40% of Nevada’s voters are Latino, Black, or Asian American Pacific Islanders, groups that tend to lean more toward Harris than Trump.

However, concerns over living costs, inflation, and immigration may tip the balance. Both parties are focusing on economic and immigration issues to sway Nevada voters in 2024.

Arizona

2020 Joe Biden won by 10,000 votes

In 2020, Arizona flipped blue for the first time in decades, with Biden narrowly winning the state.

In Arizona, voters are driven by a range of issues, including reproductive rights, immigration, education, and the economy. No single issue dominates the political landscape, making it a highly contested battleground in 2024.

Pennsylvania

2020: Joe Biden won by 82,000 votes

Pennsylvania holds 19 electoral votes, the most of any battleground state. If Harris loses here, she must win either North Carolina or Georgia—two states that have only gone Democratic three times in the past 40 years—to remain competitive.

Trump secured Pennsylvania in 2016, but Biden reclaimed it in 2020, which was critical to his win.

A September poll of 800 likely voters in Pennsylvania revealed the economy as the top concern, followed by abortion. Pennsylvania is also the state where Trump survived an assassination attempt in July.

Michigan

2020: Joe Biden won by 150,000 votes

Michigan, another key battleground state, was flipped by Trump in 2016 and won back by Biden in 2020.

At least 31 percent of Michigan voters ranked the economy as their top concern, according to a survey from Emerson College Polling and The Hill published in February.

Following that were immigration (13 percent), threats to democracy (12 percent), healthcare (10 percent), housing affordability (8 percent), education (7 percent), crime (7 percent), and abortion access (5 percent).

Wisconsin

2020: Joe Biden won by 21,000 votes

Like Michigan and Pennsylvania, Wisconsin was part of the so-called "blue wall" that Trump shattered in 2016 before Biden rebuilt it in 2020.

The state has a long history of close elections, with rural, suburban, and urban areas often pulling in different political directions. In 2024, Wisconsin is expected to be a key focal point for both parties.

North Carolina

2020: Trump won by 21,000 votes

Although North Carolina has leaned Republican in recent presidential elections, it remains a vital swing state due to its rapidly shifting demographics.

The state's recent enactment of one of the nation's strictest abortion bans, which prohibits terminations after 12 weeks, before many women even realise they are pregnant, could become a decisive factor in tipping the political balance.