America is getting angrier, according to one watchdog.

For the first time in five years, the number of hate groups in the United States rose in 2015, according to a new report from the Southern Poverty Law Center, a legal and advocacy organization known among other things for monitoring extremist activity.

The number of such groups spiked 14 percent in 2015, a year characterized by levels of polarization and anger perhaps unmatched since the political turmoil of 1968, the center said in the report on hate and extremism released exclusively to The Washington Post on Wednesday.

Swelling numbers of Ku Klux Klan chapters and black separatist groups drove last year’s surge, though organizations classified as anti-gay, anti-immigrant and anti-Muslim saw small increases, too.

“It was a year marked by very high levels of political violence, enormous rage in the electorate and a real significant growth in hate groups,” said Mark Potok, author of the report.

The center credits a number of factors for inciting that anger, including shifting demographics that largely favor non-whites; immigration; legalized same-sex marriage; the rise of the Black Lives Matter movement; and the all-too-real atrocities carried out by Islamic terrorists.

A creeping rhetoric of intolerance among politicians helped to normalize hate, the center argued. And while it singled out other presidential contenders, too, the center – which conservatives criticize for casting too wide a net – stated that Donald Trump had “electrified the radical right.”

“Hate in the mainstream had absorbed some of the hate on the fringes,” the group wrote in the report, which is published in a magazine whose cover prominently features Trump alongside domestic terrorists.

Racist extremists were responsible for the spike last year, the law center found.

The number of KKK chapters in America more than doubled from 2014 to 2015, rising from 72 to 190, according to the report. That growth was “invigorated” by several hundred pro-Confederate flag rallies, which largely channeled white anger over the group’s declining demographic and economic position, the group said.

Black separatist groups also multiplied, rising from 113 in 2014 to 180 last year, “pretty much as a direct result of the rise of the Black Lives Matter movement,” Potok said.

But unlike the members of that movement, the separatist groups represented an extreme position that “demonized” whites, gays and Jews.

The number of black separatist groups was the highest of any year since at least 2000, according to Southern Poverty Law Center data. The number of Klan chapters was the highest of all but one year – 2010 – during that time period. Those numbers exclude white nationalist and racist skinhead groups.

For all of its effort at documenting hateful association in the United States, the law center noted that its 2015 count was likely an underestimate, as extremists increasingly turn to the Internet to congregate anonymously.

Critics have suggested the opposite – that the law center overestimates the number of hate groups. A broad definition of “hate” leads the law center to cast too wide a net, unfairly ensnaring groups simply for having strong conservative views on topics such as abortion or illegal immigration, the organization’s detractors have argued.

Hate groups aside, the law center also documented a 14 percent swell in anti-government “patriot” groups – militias and others motivated by conspiracy theories. Those “patriot” groups are not necessarily violent or racist, but rather tend to fear and oppose a “New World Order” and be staunchly anti-government.

The number of such groups – counted separately from hate groups – rose from 874 in 2014 to 998 last year. The groups were emboldened, the Southern Poverty Law Center said, by Cliven Bundy’s 2014 standoff, in which he was joined by armed ranchers in facing down federal authorities over a dispute related to land rights.

As to what the future holds, the law center’s Potok notes that FBI data shows hate crimes last year rose for just one group: Muslims.

“I think that gives an indication of what’s coming,” he said.