Judith Pearson’s home in rural Minnesota is stocked with guns for hunting and recreational use, but that didn’t stop her from venting her frustration with the National Rifle Association after the deadly school shooting in Parkland, Fla.
Ms. Pearson, a retired school principal, was irked by the group’s repeated efforts to preserve civilian access to semiautomatic rifles, like the AR-15 the gunman used to kill 17 students and school staff members. “BoycottNRA,” she wrote to her handful of Twitter followers on the day of the attack, becoming one of the first participants in what became a sprawling campaign to force corporate America to dissociate itself from the gun lobby.
Across the country, in Los Angeles, Laura Mannino had a similar thought.
Drain the NRA, an advocacy group she co-founded in October after a deadly shooting in Las Vegas, developed a public spreadsheet of businesses associated with the gun group. After the attack in Florida, Ms. Mannino helped organize a rally against gun violence in downtown Los Angeles that drew hundreds of people.
“Everyone started, in parallel ways, but in tandem, to go after these companies,” she said.
Since the Parkland massacre, a range of people and coalitions have converged on the nationwide battleground over gun control. That includes individuals trying to make a statement, activist organizations sensing a shift in sentiment, informal parents’ clubs, marketing executives, niche media groups, celebrities and shooting survivors.
Through an uncoordinated but simpatico collection of Twitter hashtags, retweeted lists, Facebook groups, online petitions and carefully orchestrated campaigns, the protest has pushed a major bank, several car rental companies, two airlines and other businesses to publicly cut ties with the N.R.A.
On Monday night, the insurance broker Lockton Affinity was the latest to join a list of more than a dozen companies that includes the insurance provider MetLife, the cybersecurity firm Symantec and the automobile pricing and information website TrueCar.
Unlike hundreds of other boycotts that barely registered with consumers, the current effort has “taken on significant symbolic purpose” and speed, said Lawrence B. Glickman, a history professor and boycotts expert at Cornell University.
“This wasn’t a concerted thing — it just took off and took on a life of its own,” Professor Glickman said. “It’s stunning — nothing like this has ever happened before with the N.R.A. as far as I know.”
The #BoycottNRA hashtag, the unofficial unifier of the movement, was trending on Twitter on Friday and appeared more than 10,000 times in a single four-hour period on Monday, according to the analytics service ExportTweet.
The hashtag has floated around social media since before the Sandy Hook massacre in late 2012, usually bubbling up after high-profile mass shootings only to quickly fade after failing to inspire much action.
After the shooting at Marjory Stoneman Douglas High School in Florida on Feb. 14, two dozen tweets mentioned the hashtag, followed by three dozen more the next day.
But the calls for a boycott remained vague until last week, when lists of companies linked to the N.R.A. began tearing across social media. Posts from popular accounts were retweeted thousands of times.
ThinkProgress, a news website with a liberal bent, was among the first to spread the names, updating a list on Feb. 20 that it first published after the Sandy Hook shooting. It also published a report that the website for the N.R.A.’s official credit card was down. On Thursday, the First National Bank of Omaha, which issued the credit card, publicly confirmed its break from the N.R.A.
“Then the floodgates were open,” said Judd Legum, who founded ThinkProgress. “Lots of people began moving very, very fast.”
The pressure on companies to cut ties with the N.R.A. soon began sprouting up from various sources.
Students who survived the Parkland shooting, who have become vocal proponents of gun control — and some of whom now have hundreds of thousands of social media followers — began pressuring specific companies to follow the bank’s lead.
The massive asset manager Blackstone demanded information about the gun industry’s presence in investment portfolios. There were also calls for banks and payment processing companies to refuse firearms-related transactions.
Facebook posts and petitions from parents in Brooklyn, hiking enthusiasts and bike shops urged consumers and retailers like REI not to support CamelBak hydration packs and Bell helmets. Those brands are owned by Vista Outdoor, which also makes guns and ammunition.
Celebrities including Alyssa Milano and Denis O’Hare began backing a push to stop Amazon and other streaming sites from supporting the NRATV online video channel.
Unaware of the Hollywood campaign, Brad Chase, a communications consultant who in the past has worked with some of the brands that distanced themselves from the N.R.A., staged his own protest against Amazon after seeing screen grabs of the N.R.A.’s content streaming on its platforms.
He and a longtime friend, whose son survived the Parkland shooting, initiated a petition on Thursday that asked people to “flood Amazon’s Legal Department with calls.”
The pair hoped for 5,000 signatures. By Tuesday afternoon, they had more than 200,000.
“We know we’re not going to change this epidemic of gun violence overnight, but this is one of those things people can do right now while we wait for the slow wheels of government to take action,” Mr. Chase said.
So far, Amazon has not issued any comment related to the N.R.A.
Some companies have resisted calls to sever business relationships with the N.R.A. On Monday, FedEx said that while it disagreed with the N.R.A.’s policies on semiautomatic firearms, it would continue to offer discounts to the group’s members.
The N.R.A. itself has accused companies of “a shameful display of political and civic cowardice” and said that, “in time, these brands will be replaced by others.” Since that statement on Saturday, the divisive debate has inspired some gun rights supporters to post about joining the N.R.A., using the hashtag #TweetYourNRAMembership.
Many N.R.A. supporters have also vowed not to patronize the brands that ended relationships with the gun group.
Still, the boycott effort — parts of it organic, parts of it carefully orchestrated — was an impressive show of force against the gun lobby.
Shannon Watts, who founded the activist group Moms Demand Action for Gun Sense in America after the Sandy Hook massacre, said her group had successfully persuaded hundreds of companies like Starbucks to block guns in their stores.
The organization has more than 100,000 active volunteers it can quickly mobilize to create graphics, send email blasts and fan out over social media.
But after Parkland, Moms Demand Action adopted hashtags that others had created and cheered on campaigns that others had organized.
“The more the merrier — it’s been a cumulative effort of different groups within the same space, all putting pressure on the N.R.A.,” Ms. Watts said. “What this has shown is that it doesn’t have to be any one specific group or person — it’s more about the overall noise than any single hashtag.”