A handful of swing states usually decide U.S. presidential elections. And according to the University of Virginia Center for Politics, the 2024 presidential election could be decided by four states currently rated as “toss-ups” where either side could win: Arizona, Georgia, Nevada and Wisconsin.

Wisconsin continues to be a highly competitive battleground state in presidential elections, where tens of millions of dollars pour into the Badger State in the form of political advertising and individual contributions to the candidates.

While swing states in past elections can be determined by looking at how close the vote was in each state, determining which states are likely to be swing states in future elections requires estimation and projection based on previous election results, polling, voter turnout and other circumstances such as the strengths and weaknesses of the candidates involved. In Wisconsin, we are living in a highly competitive era of presidential politics. Here’s a brief overview of the numbers that illustrate the point in the Badger State.

Voting for the winner

In presidential electoral politics, states like Wisconsin are considered bellwethers of future electoral outcomes because of how many times they have voted for the winning candidate or party. Using statistical data from the U.S. National Archives and Records Administration, here’s an analysis of Wisconsin’s voting record in presidential elections from 1900 to 2020 from Ballotpedia. Wisconsin’s accuracy is based on how many times the state voted for the winning presidential candidate.

• In Wisconsin presidential elections from 1900-2020, there have been 15 Democratic wins and 15 Republican wins.
• Since 1900, Wisconsin has voted Democratic 48.4% of the time and Republican 48.4% of the time.
• Between 1900 and 2020, Wisconsin voted for the winning presidential candidate 77.4% of the time.
• Between 2000 and 2020, Wisconsin voted for the winning presidential candidate 66.7% of the time.
• Since 2000, Wisconsin has voted Democratic 83.3% of the time and Republican 16.7% of the time.
• Wisconsin voted for Joe Biden in the 2020 presidential election.

High voter turnout

Another feature of highly competitive battleground states in presidential elections is above-average voter turnout. For decades, Wisconsin voter turnout has been among the highest in the country. Here are the numbers for voter turnout in presidential elections since 2000.

State of Wisconsin partisan voter turnout 2000-2020

Source: Wisconsin Elections Commission

Voter turnout ranking of state

As a swing state, total voter turnout as a percent of the voting age population in Wisconsin consistently ranks in the top five states:

Voter turnout ranking of states

Source: United States Election Project

In Wisconsin, four of the last six presidential elections have been decided by less than one percentage point:

Presidential election decisions

Source: Ballotpedia

On the other hand, Barack Obama won Wisconsin by 6.7 percentage points in 2012 and 13.9 percentage points in 2008.

Tipping point state

Wisconsin tipped the scales in 2016, putting Trump over 270 in the electoral college by less than 23,000 votes. Wisconsin once again tipped the scales in 2020, putting Biden over 270 in the electoral college by less than 21,000 votes. With seven months to go until the 2024 presidential election, the road to the White House could run directly through Wisconsin as the swing state, pivotal in deciding which party emerges victorious.