Have Republicans sent Washington into a landslide? Not much.

Immediately after his November victory, President-elect Donald J. Trump asserted a “strong mandate” for his legislative agenda. In fact, he won every major battleground state by a landslide, becoming the first Republican in 20 years to win the popular vote.

But Mr. Trump’s narrowest margin in the popular vote was just 1.5 percentage points, the smallest margin since 2000 and the fourth narrowest since 1900.

In this era of competitive elections, landslide victories where one candidate enjoys overwhelming support are rare at the national level. The popular vote difference in every presidential election since 1988 has been within 10 percentage points, reflecting the country’s sharp political divisions.

For much of U.S. history, particularly strong candidates have been able to mobilize large numbers of voters to abandon their party in presidential elections.

As politics becomes increasingly polarized, both parties are increasingly using data to target voters and increase turnout. As a result, presidential elections are far less likely to result in landslides, said David Dermofal, a political science professor at the University of South Carolina.

“In such a well-informed environment, the two parties should be roughly even and close to each other’s vote share,” he said.

Big change, little gain

Last year was notable because it was the first time since 2004 that Republicans won the popular vote. The country tilted toward the Republican Party by about 6 points, one of the biggest shifts in the last 20 years.

Trump’s rise was enough for Republicans to win the popular vote, but far more than in past elections, when Jimmy Carter’s 1976 victory flipped Democrats 25 points or 23 points. This victory pales in comparison to the big changes. toward the Republican Party with President Richard Nixon’s 1968 victory.

Throughout the 20th century, it was common for the popular vote margin to swing by more than 20 points in a given election cycle. Over the past few decades, the shift has fallen to less than 10 percent.

“The continuity of today’s voting patterns is what distinguishes our electoral era from the past,” said Carlos Algara, assistant professor of political science at Claremont Graduate University. “Many of these counties were either off-target for Republicans or off-target for Democrats, and Trump really accelerated this trend.”

The declining dominance of the House of Commons

In November, Republicans held on to the House of Representatives and took back the Senate, giving Trump control of the House of Representatives.

The 119th Congress began with just four seats separating Republicans and Democrats, the narrowest start since the 1930s.

A 100-seat difference in the House of Representatives and a 20-seat difference in the Senate was not uncommon in the 20th century. Currently, there is an even closer relationship between the House of Representatives and the Senate.

The Republican majority in Congress is expected to be even closer this year, with New York Rep. Elise Stefanik and Florida Rep. Mike Walz potentially joining Mr. Trump’s administration.

narrow margin in the Senate

The Senate has seen narrowing margins over the past few decades, and the 2024 outcome will be no different.

Republicans flipped four seats in the recent Senate elections, winning races in three red states (Ohio, Montana, and West Virginia) and winning Pennsylvania, giving them a six-seat advantage.

A narrow margin doesn’t necessarily mean it will be easy for Democrats to take back the Senate. Four seats will need to be replaced in the 2026 midterm elections.