The groups and the people who support them are increasingly moving in the shadows.
[Ads /]
Instead of formally joining a hate group, people who share their ideology are connecting with like-minded people online and then carrying out attacks in the real world.
"Throughout the four years of the Trump presidency we witnessed a growing threat to our democracy. During that time the white nationalist movement surged," said Cassie Miller, senior research analyst with the Southern Poverty Law Center.
RELATED: Extremist group relishes in Trump's mention during debate
The report by the SPLC found the number of active hate groups has declined from 940 nationwide in 2019 to 838 in 2020.
The number of hate groups also dropped in California from 88 to 72, according to the report.
But the center warns not to be fooled by the numbers -- people who share an ideology with these groups are taking their hate online.
"Online spaces have really helped facilitate a more diffused structure within the far-right. Extremists can join a number of Facebook groups or Telegram channels and get the same sense that they are a part of an in group or participating in a movement as they may have gotten from joining a more formalized structure in years past," said Miller.
In California, the 72 active groups include anti-LGBTQ groups with chapters in the South Bay to White nationalist organizations like the Proud Boys.
[Ads /]
RELATED: Who are the Proud Boys? Trump's debate callout bolsters far-right group
Who are the Proud Boys?
The latter has a footprint across the state.
The group has been vocal, staging rallies at the State Capitol in Sacramento and joining the siege on the U.S. Capitol last month.
"They're out there, they're angry, they're disenfranchised. They are upset that President Trump lost," said Brad Garrett, former FBI special agent in an interview with ABC News.
These people are living among us: like Ian Rogers of Napa.
RELATED: Napa man held on $5M bond after cache of weapons, pipe bombs found at home and business
Bay Area man accused of stockpiling weapons, explosives
The FBI announced charges against him last week for allegedly plotting an attack on democrats.
According to federal authorities, he was found with pipe bombs and thousands of rounds of ammo.
It's cases like these that lead the Department of Homeland Security to release a rare bulletin last week.
[Ads /]
The department warned that the U.S. may face heightened threats from "ideologically-motivated violent extremists."
The SPLC also warns the current state of the world likely lead to extremists groups joining forces.
RELATED: Biden orders review of domestic violent extremism threat
"A number of events energized the anti-government movement. These events include COVID-19, Black Lives Matter protests, and the election cycle which have all contributed to increased activity," said Freddy Cruz of the SPLC.
Cruz added, "COVID lockdown protests created opportunities for crossover between factions of the far-right."
The center is urging the Biden administration to take action.
The SPLC recommended the administration establish offices within the Department of Homeland Security, the Justice Department and the FBI that are dedicated to monitoring and prosecuting domestic terrorism cases.
It also recommended additional education and anti-bias training.