Soon after his victory in November, President-elect Donald J. Trump claimed a “powerful mandate” for his legislative agenda. Indeed, he swept all of the key battleground states and was the first Republican to win the popular vote in two decades.

However, Mr. Trump won the popular vote by only 1.5 percentage points, the smallest margin since 2000. It was the fourth narrowest gap since 1900.

Margin of victory in presidential popular vote since 1900

Color represents the winner of the popular vote in each election.

Source: Carlos Algara and Sharif Amlani via Harvard Dataverse (1900-2020) and the Associated Press (2024)

Note: Margins are based on the difference between Republican and Democratic shares of total votes.

By The New York Times

In this competitive era of elections, landslide victories — in which one candidate receives overwhelming support — rarely happen on the national level. Since 1988, the popular vote margin of every presidential election has been within 10 percentage points, a reflection of the country’s stark political divide.

For much of U.S. history, particularly strong candidates could sway large numbers of voters to abandon their home party in presidential elections.

Now, amid deepening political polarization, both parties increasingly use data to target voters and improve turnout. As a result, presidential landslide elections have become much less common, according to David Darmofal, a professor of political science at the University of South Carolina.

“We would expect that in that better-informed environment, the two parties should be roughly in equilibrium and getting close to each other’s percentage of the votes,” he said.

Big shift, slim margin

Last year was notable because it was the first time that Republicans won the popular vote since 2004. The country swung about six points rightward toward Republicans, one of the more substantial shifts in the last two decades.

How 2024’s presidential popular vote shift compares

Length of arrows represents the shift in margin from the previous election to the current one.

Source: Carlos Algara and Sharif Amlani via Harvard Dataverse (1900-2020) and the Associated Press (2024)

Note: Margins are based on the difference between Republican and Democratic shares of total votes.

By The New York Times

While Mr. Trump’s gains were just enough for Republicans to win the popular vote, the victory does not stand out compared with much larger shifts in previous elections, like the 25-point turn toward Democrats in Jimmy Carter’s 1976 victory or the 23-point flip toward Republicans in Richard Nixon’s 1968 win.

Throughout the 20th century, it was common for the popular vote margin to swing more than 20 points in a given election cycle. In the last several decades, shifts have dwindled to fewer than 10 percentage points.

“The continuity in voting patterns today is what separates our era of elections relative to the past,” said Carlos Algara, an assistant professor of political science at the Claremont Graduate University. “A lot of these counties are just off the table for Republicans or off the table for Democrats, and Trump has really accelerated this trend.”

A waning edge in the House

In November, Republicans held on to the House and regained the Senate, handing Mr. Trump a government trifecta.

The 119th session’s House of Representatives began with a margin of only four seats separating Republicans and Democrats, the narrowest start since the 1930s.

Seat margin of the majority party in U.S. House

Color represents the majority party at the beginning of each session.

Source: U.S. House of Representatives

Note: Margins are based on the difference between Republican and Democratic seats at the beginning of each Congress. Prior to 1913, the U.S. House had fewer than 435 members.

By The New York Times

Seeing 100-seat margins in the House and 20-seat differences in the Senate was not uncommon in the 20th century. Today, they are much tighter in both the House and Senate.

The Republicans’ majority this session is expected to be even closer with Representatives Elise Stefanik of New York and Mike Waltz of Florida possibly joining Mr. Trump’s administration.

Slim margins in the Senate

In the Senate, seat margins have decreased over the last several decades, and the result in 2024 is no exception.

Republicans flipped four seats in the most recent election in the Senate, winning races in three red states (Ohio, Montana and West Virginia) and eking out a victory in Pennsylvania for a six-seat advantage.

Seat margin of the majority party in U.S. Senate

Color represents the majority party at the beginning of each session.

Source: U.S. Senate

Note: Margins are based on the difference between Republican and Democratic seats, including independent or third-party members who caucus with either party, at the beginning of each Congress. Margins do not include the Vice Presidential tie-breaking vote. Prior to 1959, the U.S. Senate had fewer than 100 members.

By The New York Times

The narrow margin does not necessarily mean it will be easier for Democrats to take back the Senate. They would have to flip four seats in the 2026 midterms.