What is the 'blue wall'? Latest polls from key states of Michigan, Pennsylvania, Wisconsin

As voters head to the polls Tuesday, many people are wondering if the "blue wall" will hold for Vice President Kamala Harris.

The blue wall refers to the collection of states that had reliably voted Democrat in recent presidential elections through 2012. In a surprising victory, former President Donald Trump flipped three blue wall states in 2016: Pennsylvania, Michigan and Wisconsin. President Joe Biden won them back in 2020.

The three states account for 44 electoral votes, a large chunk of the 93 electoral votes that the seven battleground states make up. If Harris secures all the Democratic-leaning states and the three blue wall swing states, she would reach the 270 electoral votes needed to win the White House.

But the world may not know on election night, as Pennsylvania and Wisconsin election officials are prohibited from starting their ballot counts before Election Day.

While we await election results, here is what recent presidential election polls have said about the candidates' standing in the toss-up blue wall states. (Spoiler alert: Just like the national polls, it is looking incredibly close.)

Presidential election polls 2024: Latest surveys on Harris vs. Trump before Election Day

Pennsylvania (19 electoral votes)

• New York Times/Siena College: Harris 48%, Trump 48% (Oct. 24-Nov. 2; 1,527 likely voters; margin of error ±3.5 percentage points)

• Emerson College/The Hill: Trump: 49%, Harris 48% (Oct. 30-Nov. 2; 1,000 likely voters; margin of error ±3 percentage points)

Past election results:

• 2016 presidential election results: Trump beat Clinton 48.6% to 47.9%

• 2020 presidential election results: Biden beat Trump 50% to 48.8%

Michigan (15 electoral votes)

• New York Times/Siena College: Harris 47%, Trump 47% (Oct. 24-Nov. 2; 998 likely voters; margin of error ±3.5 percentage points)

• Emerson College/The Hill: Harris 50%, Trump 48% (Oct. 30-Nov. 2; 790 voters; margin of error ±3.4 percentage points)

Past election results:

• 2016 presidential election results: Trump beat Clinton 47.6% to 47.4%

• 2020 presidential election results: Biden beat Trump 50.6% to 47.8%

Wisconsin (10 electoral votes)

• New York Times/Siena College: Harris 49%, Trump 47% (Oct. 24-Nov. 2; 1,305 likely voters; margin of error ±3.5 percentage points)

• Emerson College/The Hill: Harris 49%, Trump 49% (Oct. 30-Nov. 2; 800 likely voters; margin of error ±3.4 percentage points)

Past election results:

• 2016 presidential election results: Trump beat Clinton 47.8% to 47%

• 2020 presidential election results: Biden beat Trump 49.6% to 48.9%

See 2024 presidential election results map

Once races are called, which could be as early as 7 p.m. ET, check back here for live results.

Kinsey Crowley is a trending news reporter at USA TODAY. Reach her at [email protected], and follow her on X and TikTok @kinseycrowley.

This article originally appeared on USA TODAY: What is the 'blue wall?' Latest election polls from 3 key states