WASHINGTON (Nexstar) — In 2016, Donald Trump lost the popular vote but was elected president through the Electoral College.

If it happens again, it would mark the sixth time in United States history, and President Trump would be the first person to do it twice.

Here’s a look at the five times it’s happened:

John Quincy Adams, 1824

While Andrew Jackson won both the popular vote and Electoral College, he did not capture a majority. At that period of time, such a scenario would send the election to the House of Representatives. Through some politicking, John Quincy Adams won the vote.

Jackson quit the Senate out of protest and ran for president again in 1828. He won that race.

Rutherford Hayes, 1876

While Democrat Samuel Tilden beat Republican Rutherford Hayes by 200,000 votes, he was not able to get to the threshold needed to win the Electoral College. Because votes in some states were disputed, Congress established a commission to decide the election. Hayes was named the winner just three days before the inauguration.

Benjamin Harris, 1888

Though Grover Cleveland won the popular votes, he lost the electoral vote to Republican Benjamin Harrison.

Cleveland ran again and won the presidency in the next race.

George W. Bush, 2000

More than a century after the last instance, George W. Bush made history by winning the electoral vote and losing the popular vote by some 500,000 votes. After some back-and-forth over voting in Florida, Bush won the electoral vote 271 to 266.

Donald Trump, 2016

Although Trump lost the popular vote by 2.8 million ballots, he earned 304 electoral votes to defeat Hillary Clinton.

Trump lost the popular vote by the greatest margin of anyone elected to the presidency.