Former President Donald Trump and Vice President Kamala Harris are heading into Election Day with razor-thin margins separating them in the handful of states that will ultimately decide the winner.

The 2024 election map bears some similarities to the landscape that Trump encountered in 2020, when he was defending the White House from a challenge by Joe Biden.

Trump is hoping to win back states that he captured in 2016, when he punctured the Democratic "blue wall" en route to the presidency. Harris is hoping to retain the states that Mr. Biden won, which would give her a comfortable victory in the Electoral College.

The 2020 Electoral College map

In 2020, Mr. Biden won 81,284,666 votes nationwide, compared to Trump's 74,224,319.

But the presidency is won in the Electoral College, not the popular vote. Mr. Biden bested Trump by that measure, too, winning 306 electoral votes to Trump's 232. A majority in the Electoral College — 270 votes — is needed to win the White House.

The Biden campaign built a coalition that helped him recapture once-reliable blue states that Trump had flipped in 2016, returning Wisconsin, Michigan and Pennsylvania to the Democratic column. He also picked up Arizona and Georgia to solidify his victory.

This map shows the states that Trump and Mr. Biden won in 2020:

For 2024, CBS News considers seven states to be battleground states that will largely decide the race. Those states are:

Arizona

Georgia

Michigan

Nevada

North Carolina

Pennsylvania

Wisconsin

Pennsylvania's 19 electoral votes make it the biggest prize of the night — a victory there makes winning the necessary 270 electoral votes much easier for either candidate.

How the electoral map has changed since 2020

The Electoral College votes are apportioned based on each state's representation in Congress. Every state gets at least three votes — one for each of their two senators, and one for each representative in the House. (This gives smaller states outsized influence on the result, since a state like Wyoming or Vermont is guaranteed more electoral votes than it would receive if they were divided strictly by population.) The District of Columbia also gets three votes, although residents have no voting members in Congress.

The electoral votes are reapportioned every 10 years as states gain or lose House seats based on their fluctuating populations. Those determinations are made by the results of the U.S. Census. If a state's population increased relative to other states, it might gain a seat or two. If its population decreased, a seat might go elsewhere.

Six states gained electoral votes in the 2024 race: Colorado, Florida, Montana, North Carolina and Oregon gained one each, and Texas gained two. Conversely, seven states lost a vote: California, Ohio, Michigan, New York, Pennsylvania and West Virginia.

Here is a look at where states have gained and lost Electoral College votes since 2020: