We have to congratulate Donald Trump on one thing; he continues to stir political passions like I have never seen in my 25 years in America. Dinner party hosts know to ban all mention of him until coffee is served lest their best china gets smashed. Arguments break out spontaneously between strangers at the laundromat. Children and parents tacitly agree just not to go there.

To someone from Europe with its traditions of union struggle, strikes and marches, America in the Nineties and Noughties seemed strangely lethargic about its politics. It is as if all the energy that might have gone into protesting the loss of jobs overseas or the raping of the middle class by Wall Street never found a way out. Trump pricked that volcano and… boom. Some of the boiling lava bore him to the White House. But now new flows threaten to incinerate him.

The bawling match that different sides of America are now engaged in seems invigorating, by comparison, though it’s hardly clear where it will eventually take the country or its political parties.

Milling through the throngs at City Hall in Los Angeles for a May Day rally – itself a surprise event, since for most Americans those two words combined mean plane crash not workers’ struggle – was to see the ongoing battle in the raw. First there were the speakers on the stage, taking the microphone one after another all afternoon long to rail against the Trump agenda under a giant banner declaring, “RESIST”. Even Mayor Eric Garcetti had his two minutes.

Listing all the grass roots groups represented would take us to the weekend. But here are a few of them: All Saints Church, Pasadena, ANGELENOS FOR TOMORROW, Asian Americans Advancing Justice, Democratic Socialists of America, CLEAN car wash campaign (I have no idea either), Communist Party USA, Church Without Walls. You get the idea, and I'm only at letter C. The last one: Writers Guild of America (who just voted against a strike).

At the afternoon’s end a few remain to hear speeches from the main stage (David Usborne)

“Los Angeles will stand up against any attempt to scapegoat immigrants, break up families, and create a climate of fear that unsettles our communities and disrupts our economy,” Garcetti intoned. “Americans are taking to the streets of LA and cities across the country on May Day because we are uniting around a principle that speaks to who we are: working people who have built their lives in this country deserve protection, compassion, and equal justice.”

Turning away from the stage, I found even more stripes of anti-Trump anger. Healthcare workers against Trump. “Undocuqueer” against Trump (though the bearer of that banner declined to talk to me.) Gray Wolf introduced himself as the director the American Indian Movement of Southern California. Bearing a long staff festooned with eagle feathers and buffalo hair, he had come with the message that Trump is the illegal who should be deported. “Mr Trump is the immigrant and Mr Trump’s people should go home,” he told me. “We need to get that straightened out.”

But the area around City Hall, helicopters buzzing about in the clear blue sky, was not reserved for the Trump resistance only. Half a block from the stage, a nub of pro-Trump folk had gathered to voice their loud disdain. “Commie scum go home,” a small woman chanted. All that was separating her and her “Make-America-Great-Again” friends from an instant pummeling was an unbroken chain of LA police in full riot garb.

An anti-Trump protestor strolls away from the main stage (David Usborne)

“They label themselves as anti-fascists but in reality but they are just fascist all the same,” a young man behind a menacing skull mask and goggles explained. Uniting this group was their embrace of Trump’s tough anti-immigration stance. “That border is very porous and it’s not just Latin Americans coming over, it’s not just Mexicans coming over, we are not trying to demonise South America or anything of that nature,” offered Nikki, who supports building the wall. “That border is so porous people of all nations are coming over, Chinese coming over, Middle Eastern.”

It was too much for Raoul Salinas, 63, an undocumented immigrant from Mexico who had taken a day off form his moving company job to join the anti-Trump crowds. He pointed angrily at Nikki and her crew. “They think only they are USA. We are USA too,” he wailed. “They hate Mexicans because for these people we are only criminals. I love Los Angeles.”

He was lucky not to come face to face with Kaila Truth, also on the other side of the street and argument. “They have no right to be in our country demanding things, we are black Americans, we were born of the United States,” she spat. “I did not see any immigrant from any country sitting on the bus with Rosa Parkes… these people have no right to come to our country and try to take over our homeland. This is our homeland for the American people, not immigrants.”

There was also something nearly joyous about the scene. Street vendors pushed through with sliced mango treats and hot sausages in carts topped by colourful shade umbrellas. A drag queen, who was not actually in drag, had requisitioned part of an intersection to dance and twirl to Donna Summer songs, a crucifix in one hand and a sign in the other that just said, “LOVE”.