Data: What are the Historical Voting Patterns in Key U.S. Swing States?

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Despite nearly 240 million Americans being eligible to vote in the 2024 U.S. Presidential Election, the outcome might hinge on just a fraction of them. While most states have predictable voting patterns, these “battleground states”, often referred to as ‘swing states’ play a critical role in determining the winner. But what does data tell us about the historical voting patterns in these swing states and other key states? Here is a deep dive.

The United States of America’s Presidential election is scheduled for 05 November 2024. In U.S. politics, the president is not elected directly by the popular vote but through a system called the Electoral College, a constitutionally established institution. Each state is allocated a certain number of electors based on its population. The number of electors from a state is equal to the sum of the number of house seats in that state and the number of senators in the state. In addition to the 535 electors from the 50 states, the seat of Government of the United States government which is the District of Columbia (commonly referred to as Washington, D.C) is allocated three (3) electors. The number of electors allocated to Washington, D.C. cannot be more than the state with the smallest number of electors as per the 23rd  amendment to the U.S. Constitution in 1961. To win the presidency, a candidate needs to secure at least 270 of the 538 available electoral votes. Factly’s explainer on US Presidential Elections can be found here.

In today’s story, we look at some trends regarding the Presidential elections.

What are ‘Swing States’?

Despite nearly 240 million Americans being eligible to vote in the 2024 U.S. Presidential Election, the outcome might hinge on just a fraction of them. While most states have predictable voting patterns, these “battleground states”, often referred to as ‘swing states’ play a critical role in determining the winner, with the rest being “spectator states”.

Swing states are known for their unpredictable voting behaviour, but this status is not permanent. A state that was once fiercely contested could become a safe haven for one party, while traditionally secure states might unexpectedly open up to competition. These shifts often arise from changing demographics, regional realignments, or evolving voter priorities. As a result, these states become battlegrounds where candidates pour their time, money, and efforts, hoping to capture the unpredictable but vital support they offer.

In this high-stakes battle, it’s not just about winning votes but about winning them in the right places. A candidate who can secure majority support in the swing states—where every vote counts—while maintaining strength in their strongholds, has the strategic edge needed to claim victory.

Why ‘Swing States’ are important?

As of 2020, there have been 59 presidential elections in U.S. history. In the 2020 election, Joe Biden secured over 80 million votes (approximately 51.3% of the total votes cast), making him the first U.S. presidential candidate to receive more than 80 million votes. His 4.5% popular vote margin of victory was the largest in the past six elections, aside from Barack Obama’s seven-point margin in 2008.

However, winning the popular vote does not guarantee the presidency. In U.S. history, there have been only five instances where a candidate lost the popular vote but still won the presidency.

In the 2016 U.S. Presidential Election, Donald Trump won 46.1% of the popular vote, trailing the Democratic candidate by approximately 2.1% in terms of popular vote, who received 48.2% votes. Despite this, Trump secured a significant advantage in the Electoral College, winning 304 electoral votes compared to the Democrat’s 227—a difference of 14%. Similarly, in the 2000 presidential election, George W. Bush trailed his opponent in the popular vote by 0.51% but led in the Electoral College, winning 271 votes to the Democrat’s 266, resulting in a 0.9% electoral margin advantage.

Hence, winning in the right places is of utmost importance, which is why swing states become key battleground states in any Presidential Election.

10 States hadn’t changed their voting preference since the 1976 Presidential Elections

In the current electoral system, a small number of votes in specific states often decide the presidential race. However, swing states are not fixed; they shift as economic and demographic factors alter population patterns. Since the 1968 elections, nine U.S. states—Alaska, the District of Columbia, Idaho, Kansas, North Dakota, Oklahoma, South Dakota, Utah, and Wyoming—along with Minnesota since 1976, have consistently maintained their voting preferences.

Meanwhile, six states—Alabama, Arizona, Mississippi, Montana, South Carolina, and Texas—have each shifted their voting preference only once since the 1976 elections either returning to their previous pattern or establishing a new one.

7 States projected to be ‘Swing States’ for 2024 Presidential Elections

Seven key states—Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania, and Wisconsin—are expected to play a crucial role in determining the outcome of the 2024 presidential election. In both 2016 and 2020, these states saw extremely tight races, with victory margins frequently below 1%. In Arizona, Georgia, Michigan, Pennsylvania, and Wisconsin, Republicans secured wins in 2016, but Democrats managed to flip them in 2020.

North Carolina was a Democratic stronghold from 1876 to 1964 but shifted to vote mostly Republican from 1980 onward, until Barack Obama’s win in 2008. Meanwhile, population growth in Nevada has turned it into a key battleground, with Hillary Clinton narrowly defeating Donald Trump in 2016, though Joe Biden won it by 2.5% in 2020. Arizona, a Republican-leaning state since 1952 (except for Bill Clinton in 1996), saw Trump win by a slim margin in 2016, but Biden flipped the state by 0.3% in 2020. Georgia, solidly Republican from 1972 to 2016 (except when a southern Democrat ran), became competitive, with Biden edging out Trump by 0.2%, the closest margin in the country. Michigan, which voted Republican from 1972 to 1988, was part of the Democratic “blue wall” from 1992 to 2012 before Trump narrowly won it in 2016 by 0.2%. Biden brought it back to the Democratic side in 2020 with a 2.8% lead. Pennsylvania, a traditional battleground, voted Democratic from 1988 to 2012 but swung to Trump in 2016 by 0.7%. Biden reclaimed it in 2020 with a 1.2% margin, reflecting the competitive nature of these key states.