Federal, state and local law-enforcement agencies across the U.S. are bracing for the possibility of a protest by truckers that could begin this weekend and carry into March, potentially including a cross-country caravan and disruptions to cities and major transportation routes.

Although it’s still not clear how serious the threat is, the U.S. Department of Homeland Security warned law-enforcement agencies that protests could begin Feb. 13, when the Super Bowl is played in Los Angeles, and arrive in the nation’s capital in early March. Truckers could time their protests to coincide with President Joe Biden’s State of the Union Speech on March 1, according to a law enforcement alert. 

“While there are currently no indications of planned violence, if hundreds of trucks converge in a major metropolitan city, the potential exists to severely disrupt transportation, federal government operations, commercial facilities, and emergency services through gridlock and potential counterprotests,” according to the Department of Homeland Security alert obtained by Bloomberg News.

Social-media channels are buzzing with the plans for a convoy to protest vaccine rules in solidarity with Canadian drivers who have occupied the center of Ottawa and blocked a key border crossing to Detroit, further disrupting crucial supply chains and raising the political pressure on Prime Minister Justin Trudeau. 

In a statement, the White House said that DHS is monitoring reports of similar convoys in the U.S., and is taking steps to ensure that they don’t disrupt lawful trade and emergency services. DHS is providing extra staff to ensure Super Bowl safety, according to the statement.

Despite the DHS alert, the actual timing of any protest appeared unsettled. A press release widely circulating on social media said the so-called People’s Convoy would begin with rallies in Indio, California, on March 4-5 featuring “top doctors” and “supportive police,” followed by a cross-country trek to Washington, possibly clogging major transportation arteries in the process. The release is attributed to “Organizers of the People’s Convoy” but lists no contacts.

Kris Young, administrator of a Facebook group called “The People’s Convoy” with more than 62,000 members, said in a message on Thursday “there is no intention or plans to go to the Super Bowl in Los Angeles. Such notice and rumor are put out by either another group or paid opposition.”

The New York Times cited one person as helping organize the event, calling it a show of solidarity for health-care workers, police and military personnel facing vaccine mandates. 

Asked about the potential protest, a spokeswoman for the District of Columbia police said officials are monitoring the possibility of “First Amendment activities” that the department expects March 1. No permit has been requested.

The White House said it has no indication that individuals behind the Washington event are engaged in anything other than First Amendment-protected activity.  

DHS Secretary Alejandro Mayorkas and Transportation Secretary Pete Buttigieg spoke with their Canadian counterparts Thursday morning, according to the White House statement, urging a resolution to the standoff in Canada that has shut down a key bridge.

In recent years, many political protests have erupted after bubbling up from online chatter. The 2021 attack on the U.S. Capitol, parades of boats and trucks filled with supporters of Donald Trump and Black Lives Matter demonstrations all were enabled or boosted by extensive online planning and discussion. Tucker Carlson, a popular Fox News personality, has discussed the possibility of protests similar to Canada’s on his evening show.

The U.S. truckers, much like their Canadian counterparts, appear to have a loose amalgamation of grievances, including a COVID-19 vaccine mandate for those entering Canada. While the protests originated in Ottawa, they later spread to the Ambassador Bridge connecting the Canadian city of Windsor with Detroit. 

At least six auto plants near the U.S.-Canada border have temporarily halted work as a result of the disruptions. 

Planning for a U.S. convoy has taken shape mostly online, using a combination of mainstream social media, messaging apps and chat rooms. On Telegram, an encrypted messaging service, all 50 states have organizing groups that have been sharing information, such as a tip to use only citizen’s band radios during the convoy in case phone signals are cut.

In the past week pro-trucker groups have accused Meta Platforms Inc., the parent company of Facebook, of suppressing information by shutting down pages related to the convoy.

Opposition to government mandates isn’t against Meta’s policies, according to a company statement, but it has removed groups and pages for violating policies prohibiting conspiracy content and those run by spammers.