After 100 days of dissent in D.C., the boundaries between cities, states and even countries have dissolved as protesters swap tactics, share strategies and ping from one demonstration to the next.

The protests after the killing of George Floyd have developed a language and shared culture as daily demonstrations become a fact of life in cities across the country. Enraged by the backdrop of police violence and racial inequality that plays out in graphic videos depicting police brutality against Black citizens, protesters have developed new means of resistance experts say may change protests in the country forever.

Marches have grown more confrontational — cornering politicians in their homes and heckling strangers as they go about their lives. Protesters have embraced mobility and taken to participating in demonstrations far from their hometowns. Some fly, some drive — some have walked for days.

Online tutorials about crafting homemade shields to protect against rubber bullets and stinging pepper ball pellets using plywood, foam pool noodles, trash can lids and other household items have spread like wildfire.

What were once considered obvious markers of troublemakers looking to break things have become muddled as demonstrators scramble to protect themselves.

Influenced at first by the longevity and intensity of Hong Kong’s pro-democracy demonstrations, then by the evolving tactics of protesters in American streets, experts say the mainstreaming of ideas and tactics once considered unusual reflects a political sea change spurred by a youth-led uprising.

“This is bringing people into a different way of being,” said Mark Bray, a Rutgers University historian and former organizer of the Occupy Wall Street movement. “Things are happening now at a profound level.”

While the nation’s capital braces for protests in the days and weeks ahead, months of unrelenting demonstrations, mass arrests and standoffs with police have changed D.C. protesters in ways big and small: Their tools, their tactics and their tolerance for behavior once decried as antithetical to peaceful protest have shifted.

On recent nights, as smoke and explosions ripped through the night air and police advanced on a line of demonstrators while shouting, “Move back,” it became clear that the flash bangs just don’t work like they used to.

Longtime demonstrators in D.C. have stopped sprinting for cover. They kick sparking canisters back toward police, walk steadily away from the rapid pop of rubber bullets and strap on respirators and gas masks when the threat of tear gas hangs in the air.

The protests have also given first-time demonstrators an up-close look at munitions, controversial crowd control tactics like “kettling” — when police surround a group of demonstrators and arrest them en masse — and the use of chemicals that make people cough, gag, cry and burn.

But images captured at these events also serve a tactical purpose: With every video of a protester disarming a tear-gas canister or volleying a smoking stun grenade back at law enforcement, demonstrators are learning skills that may have otherwise taken months to acquire on their own.

Like the civil rights movement of the 1960s opened Americans’ eyes to racism and the Occupy Wall Street movement turned socioeconomic inequality into a national conversation, experts say the Black Lives Matter movement’s protests will probably shape the worldview and politics of a generation — and forever influence the way Americans protest.

It also moves the needle of what is considered a peaceful protest, said Gabriella Coleman, an anthropologist at McGill University in Montreal who specializes in online activism and social movements.

Coleman said as more videos of violent standoffs are shared on social media, “they become so common or seen as so unremarkable” that people get used to it.

“It allows this transmission and normalization that is almost unconscious,” she said.

In the same way videos of violent police encounters with unarmed Black men and women have driven many Americans to recalibrate their views on policing and criminal justice changes, so, too, have videos of protesters being pushed, shot at and tear-gassed, Coleman said.

Since protests began in late May, public officials have sought to draw clear distinctions among groups of people: The good protesters and bad protesters; the looters, the vandals and the peaceful demonstrators — but it has never been that simple.

“Protesters who were relatively new to protest and who, by now, have been shot with rubber bullets and pepper spray have now learned what kind of helmets to wear and what to do with a tear-gas canister that lands at your feet,” Bray said.

D.C. Mayor Muriel E. Bowser (D) has pointed to agitators who she has long said come from outside the city bent on destruction. President Trump has intensified his efforts to demonize the far-left antifa movement for escalating demonstrations, property damage and violence in Democrat-run cities.

Last weekend — after a peaceful gathering of thousands in D.C. at the 2020 March on Washington — a chaotic standoff ensued between protesters and D.C. police, who fired rubber bullets and noxious chemicals into a crowd.

More than two dozen people were arrested. Police said officers were injured by bricks, fireworks and lasers pointed into their eyes.

Bowser blamed “outside agitators” for setting fires and shooting off fireworks in overnight clashes. These visitors had come “armed for battle,” Bowser said, “looking for police to confront.”

Of 29 people arrested, most were from the Washington area, including the Maryland and Virginia suburbs, according to arrest details released by police.

After the daytime march ended, some visitors from other states attended smaller rallies to disrupt Washingtonians’ daily lives and confront residents on issues of race and criminal justice.

Video taken on Aug. 24 shows a group of protesters heckling a diner at an outdoor restaurant in Washington, D.C., urging her to raise her fist in solidarity. (The Washington Post)

Hundreds of protesters roved though city streets, blocking bridges, highways and swaths of downtown traffic. By the end of the day, after marches had spent hours crisscrossing the city, a D.C. organizer called out to the unfamiliar faces in the crowd: “Do y’all need any help getting back to your hotels or Airbnbs? Just ask us.”

Despite the coronavirus pandemic, protest-hopping in different cities has become an increasingly common practice among the most committed activists.

They travel to the sites of recent police killings — like the D.C. police shooting of 18-year-old Deon Kay in Southeast Washington and asphyxiation of Daniel Prude, who died after officers put a black hood over his head and pinned him face down in the street — where inflamed tensions spark nightly clashes.

Some join in demonstrations, while others offer food and supplies, help get protesters out of jail or offer aid to local organizers. Several protesters said these experiences can be transformative — a way to learn new strategies and new ways to organize.

D.C. activists have participated in protests in Richmond and New York, among other cities. Members of the fledgling Freedom Fighters D.C. organization are planning trips to Denver, Portland, Ore., and Kenosha, Wis., organizer Arianna Evans said.

As demonstrators broaden the definition of what it means and looks like to protest, Bray said, the public’s idea of what constitutes acceptable resistance has also changed.

When leaf blowers cropped up in Portland, allowing demonstrators to clear the air of the tear gas federal forces were using to blanket downtown streets, the “leaf-blower dads” were thanked and celebrated by protesters and onlookers.

Now, leaf blowers are becoming a feature of protests around the country.

“Prior to this decade, I’d say that for most Americans, acceptable protest was holding a sign or voting. The center of gravity has been shifted by pushing protest tactics in a more militant direction,” Bray said. “It really complicates our picture of what is or is not violent protest.”

Laser pointers, which have been used to foil surveillance cameras and drones from Hong Kong to American cities — and to injure officers, police say — are less universally embraced, Coleman said. Last month in D.C., several protesters pointed lasers at the line of police staring them down.

Video taken on Aug. 27 showed a tense situation between a White man and a group of protesters during a demonstration in Washington, D.C. (The Washington Post)

Even chants seem to travel from city to city.

In D.C., protesters from different states recently greeted each other with a call and response that protesters around the country repeat in marches through their own communities.

“Who keeps us safe?” they ask.

“We keep us safe,” comes the reply.

Jeremy Vajko, 27, a software engineer from Seattle, was one of many protesters who came to D.C. last month from out of state. Vajko emerged from the D.C. jail Monday to chants and cheers from local activists who celebrated their release.

Although Vajko was in an unfamiliar city surrounded by new people, the solidarity and generosity felt familiar. Vajko, who identifies with the gender-neutral “they” pronoun, said they have felt similar sentiments in every city while driving a van to protests in recent months.

Vajko was arrested during D.C. protests in late August while their white van — known among protesters as the Snack Van — was bashed by police.

The van is hard to miss. It’s covered in “Black Lives Matter” graffiti and has traveled from state to state to offer food, water and emotional support to activists calling for racial justice.

Vajko and the Snack Van became a fixture earlier this year at Portland protests, where they joined an elaborate aid effort that handed out food and water.

After leaving a job in the tech sector this year, Vajko cashed out their retirement savings and spent $50,000 to maintain the van, which has been attacked by white nationalist armed groups and targeted by police, Vajko said. More than once, the windows have been shattered and the van shot at with less-lethal rounds. The inside was bear-maced once, Vajko said, ruining heaps of food and contaminating supplies.

“I don’t show up to create violence. I show up to help people,” Vajko said. “Obviously, the solution to all this is not for me to just show up with food everywhere, but it feels like it’s something I can do to help right now.”

Vajko was arrested twice in Portland. A D.C. police officer last month was filmed shattering the driver’s side window of the van and pulling Vajko out onto the sidewalk. Vajko was arrested Saturday and held through Monday, when they were told the U.S. attorney’s office would not be pursuing criminal charges.

The next day, Vajko piled back into the van and charted a course for Kenosha.

Driving from place to place, protest to protest, has given Vajko a front-row seat to the proliferation of protest tactics that were once a hallmark of West Coast radicals.

“That fight is now showing up across America, and they’re seeing how Portland has dealt with it,” Vajko said. “People are traveling to other cities to learn how to protest and then coming back.”

Evans, the Freedom Fighters D.C. organizer, can’t wait to go to Portland.

A Howard University student who has been protesting since Floyd’s killing, Evans used to consider herself a “peace activist.” Known for her vivid red braids that cascade down her back as she commanded a megaphone, she routinely implored fellow demonstrators to “stop throwing [stuff]” like water bottles at police.

In the first week of D.C. protests, as she was tear-gassed and pushed out of Lafayette Square by federal agents, Evans denounced violence and agitation, saying, “The more that we are violent, the worse this will get for every one of us who is out here.”

Now, she talks about trash can fires set in the city and shrugs.

Police are still shooting at unarmed protesters, she said. Onlookers and peaceful demonstrators are tear-gassed as badly as those who light a spark.

“I was out here fighting for peace, asking people not to be aggressive, saying, ‘Don’t do anything,’ and then I got shot at by rubber bullets. Then I got tear-gassed and pepper-sprayed, and it showed me that crime is a social construct because [the police] can openly violate our rights and that’s not illegal, so now I feel like it’s well within our rights to fight back as hard as we can,” she said. “People might say I’ve been radicalized, but you know what? I have absolutely been radicalized — and it’s the government’s fault.”