The most important political trend in U.S. public opinion is the intense polarization of Americans, which is more severe than it's been for a generation, a new poll says.

The survey by NBC News and the Wall Street Journal also finds that President Donald Trump has become the most divisive president in the history of polling.

The survey was designed to examine the major social and political trends of the past generation. Republican pollster Bill McInturff, who helped conduct the poll, said "the most important trend impacting our politics" is "the increase in political polarization."

The pollsters told reporters, "President Reagan was noteworthy for being the most polarizing president in modern polling history. President Reagan's status was then eclipsed by President Clinton. ... Each successive presidency after President Clinton then became the most polarizing in polling history." The pollsters added: "President Trump's historically low ratings among Democrats is an important finding but needs to be understood as the logical conclusion of a generational trend."

Under Ronald Reagan, 85 percent of his fellow Republicans approved of his job performance at the eight-month mark of his presidency in 1981, while 42 percent of Democrats disapproved, a gap of 43 percentage points.

The gap closed under George H.W. Bush in 1989, with fellow Republicans giving him 83 percent approval and Democrats giving him 59 percent, a margin of 24 points at his eight-month mark.

Then the gap started to grow again.

Bill Clinton, a Democrat, had the approval of 70 percent of fellow Democrats and only 20 per cent of Republicans, for a 50 percent gap in 1993.

George W. Bush, a Republican, had the approval of 87 percent of fellow Republicans and 21 percent of Democrats, for a 66-point differential in 2001.

Barack Obama, a Democrat, had 86 percent approval in his party and 16 percent among Republicans, for a 70 percent gap in 2009.

President Trump, a Republican, has experienced the worst polarization. Eighty percent of Republicans approve of his job performance and only 8 percent of Democrats approve. for a 72-point gap at the eight-month mark.

Among other findings of the NBC/Wall Street Journal pollsters:

The percentage of Americans who favor allowing same-sex marriage has doubled from 30 per cent to 60 percent during the past 13 years.

Fifty percent of Americans are concerned the government will go too far in restricting gun rights, up from 35 percent in 1995. (The survey was taken prior to this week's shootings in Las Vegas.)

The percentage of Americans who say they never attend religious services has risen to 24 percent from 13 percent in 1999.