Can 0.03% of US votes really swing the presidential election?
In recent years there has been growing criticism of the electoral college system in the US because it has allowed a tiny number of Americans to determine the outcome of the presidential election.
In 2020, about 43,000 votes among Wisconsin, Georgia and Arizona – a mere 0.03% of the votes cast nationwide – allowed Biden to win. In 2016, about 80,000 combined votes gave Trump his winning margins in key swing states.
How does this happen? How is such a slim margin so decisive in an election in which 154.6m votes are cast? Here’s how it works.
Biden vs. Trump
Popular vote winning margin, %
Popular vote winning margin, %
per state district
Source: Federal Election Commission, 2016 and 2020 results
Footnote: Maine and Nebraska allocate two electoral college votes to the statewide winner. Each state then awards its remaining electors – two in Maine and three in Nebraska – to the winner in each of the state’s congressional districts.
Each US state is assigned a certain number of electoral college votes; some states have more than others. To win the US presidency, a candidate has to win more of these electoral college votes than their opponent. This means that when they win the popular vote in an individual state, they get the electoral college votes assigned to that state - represented here by the height of each block. Block by block, a candidate needs to reach a majority of 270 to win. In 2020, Biden earned 306 electoral votes.
Not all states are won in the same way, though. Let’s rebuild our towers so that each block’s width reflects the margin of victory — or the extent to which each candidate won the popular vote in each state.
Narrow blocks were won by close victories, wider ones represent landslide wins.
Both Biden and Trump had some states where they won by a comfortable margin of more than 20% of the popular vote. For Biden, this included populous states like California and New York, which gave him 55 and 29 electoral college votes respectively.
Both candidates also secured other states where they won by a margin of between 5 to 20% of the popular vote. For Trump, whose landslide victories tended to happen in less populous states, this meant winning Texas’s extensive 28 electoral votes with a majority of only 5.7%.
But in 2020, this wasn’t enough to get to a majority of 270 electoral votes. Joe Biden won the presidency with three states in which he had a lead of less than 1%: Georgia, Arizona and Wisconsin. Combined, this meant he won the presidency with 43,000 popular votes.
Trump secured his victory in 2016 in a similar way. His lead in Michigan, Pennsylvania and Wisconsin was less than 1% of the popular vote, but this was enough to give the Republicans the last needed 46 electoral college votes.
The challenge in 2024
Presidential candidates need at least 270 electoral votes – more than half of the total – to win an election. As narrow victories can get parties over the line and determine the election, those states with very close wins, often called “swing states”, get special attention from pollsters, campaigners and pundits.
In the 2024 election, there are six swing states: Pennsylvania (19 electoral votes), Wisconsin (10), Michigan (15), Georgia (16), Arizona (11) and Nevada (6). The Harris campaign also considers North Carolina, usually a Republican state in the presidential race, and its 16 electoral votes to be competitive. Whichever candidate wins the election must carry some combination of those states.
The idea of a swing state can also change over time with shifting demographics and political trends. Until recently, for example, Ohio and Florida were considered swing states, but they are now considered to be pretty solidly Republican. Michigan was considered a relatively solid Democratic stronghold until Donald Trump won it in 2016.
Over the next few months, Donald Trump and Kamala Harris will spend most of their time campaigning in these states, knowing that these voters will determine the outcome of the election.
Criticisms of the electoral system
These very narrow wins in recent elections add into the growing criticism that the power of a presidential vote depends on where one lives.
The least populous states, such as North and South Dakota, and the smaller states of New England are overrepresented because of the required minimum of three electoral votes.
Electoral votes are assigned to each state according to their population. But then each of them gets two more to represent their Senate seats – which means less populous states get a minimum of three electoral votes, regardless of the size of their population. Meanwhile, the states with the most people – California, Texas and Florida – are underrepresented in the electoral college.
This means that while one elector in Wyoming represents 195,000 people, in a state like Texas, one elector represents 763,000 people.
This has become more relevant in recent times, as during the last 20 years the number of states won by margins of more than 15% – a landslide win – has increased.