There are believed to be seven states that could potentially be won by either candidate. As a result, the campaigns of Vice President Kamala Harris and former President Donald Trump have focused their energies in these areas.

They can be divided into two general categories:

3 battlefields in the Midwest, also known as ‘the blue wall’ – These are the manufacturing and union-rich states of Pennsylvania, Michigan and Wisconsin. They used to be more reliably Democratic, but they have changed as their populations changed and Trump appealed to white voters without a college degree.

When Trump won the White House in 2016, he won all three. When Joe Biden won in 2020, he won all three. If Harris wins all three elections this year, she likely has the electoral votes to become president. But polls indicate close races in all three countries. Turnout will be crucial, which for Harris means appealing to suburban women and black voters.

The blue wall states generally vote the same way. The last time they didn’t all go to the same candidate was 1988 – especially a year when California was red and West Virginia was blue. In those eight elections since 1988, the only time the blue wall states went to a Republican was in 2016, when they were won by Trump.

4 Sun Belt Battlefields – These states with growing populations include Arizona and Nevada in the West, and North Carolina and Georgia in the East. Arizona, Georgia and North Carolina used to be more reliably Republican. Trump won North Carolina twice, but the margins were close in 2020. The last Democrat to win there was Barack Obama in 2008. Biden was the first Democrat to win Georgia since Bill Clinton in 1992 and Arizona since Clinton in 1996.

One vote in Nebraska is a battleground — 48 states award all their electoral votes to the victor. Nebraska and Maine do it differently, awarding votes by congressional district. The state of Nebraska is safe Trump territory, but the congressional district around Omaha is a battleground. That one vote could be crucial in the event of a close battle in the Electoral College.

Remark: It’s the reverse situation in Maine, the only other state that doesn’t award all its electors to the statewide winner. Trump could win a single electoral vote in Maine.

Read more about how US elections work.