Across big cities and small towns on Saturday, millions of Americans poured into the streets in a sweeping, coordinated protest against President Donald Trump, in what organizers of the “No Kings” movement said could become the largest day of demonstrations in the nation’s history.From New York to California, and from rural Kentucky to the nation’s capital, demonstrators marched, chanted and waved signs denouncing authoritarian overreach, war in Iran and an aggressive immigration crackdown that has roiled communities and national politics alike. More than 3,000 events were planned nationwide, with turnout expected to surpass the estimated 5 million to 7 million people who participated in earlier rounds of protests over the past year.Read more: 'No Kings' Protests May Draw Biggest—and Most Diverse—Anti-Trump Crowds EverBy midday, the flagship rally in Minnesota was already underway, with at least 50,000 people gathered at the State Capitol in St. Paul. Organizers had promised a high-profile lineup of speakers and performers later in the day, which included Senator Bernie Sanders, Jane Fonda, and Bruce Springsteen, who performed “Streets of Minneapolis,” a song he wrote condemning the Trump Administration’s federal immigration raids. “Your strength and your commitment told us that this is still America, and this reactionary nightmare and these invasions of American cities will not stand,” Springsteen said to the crowd. “You gave us hope. You gave us courage, and for those who gave their lives, Renée Good, mother of three, brutally murdered, and Alex Pretti, a VA nurse executed by ICE, shot in the back and left to die in the street without even the decency of our lawless government investigating their deaths—their bravery, their sacrifice and their names will not be forgotten.”Mixed grievancesThe demonstrations, organized by a loose coalition of activist groups under the “No Kings” banner, reflected a broad constellation of grievances rather than a single demand. Some protesters aimed their criticism at Congress, chanting “do your job” and carrying signs that mocked lawmakers as timid or unwilling to stand up to the Trump Administration. Protesters pointed to the war in Iran, as well as a protracted government funding standoff over immigration enforcement that has left airport security lines snarled and federal workers unpaid. Others decried proposed changes to voting laws, environmental rollbacks, and what they see as a steady erosion of democratic norms.In Washington, D.C., a stream of protesters marched from Arlington, Va., to the National Mall, beating drums and ringing cowbells as they chanted, “No justice, no peace. No ICE in our streets.” Some carried oversized puppet heads of Administration officials. An inflatable effigy depicting Trump defacing the Constitution made its way through the crowd.In New York, marchers filled Midtown, spilling into Times Square. In Atlanta, demonstrators called for an end to immigration raids. In Boston, protesters erected a memorial honoring children killed in a recent missile strike in Iran, which the U.S. was reportedly responsible for, according to The New York Times.'Just a start'The protests appeared to be largely peaceful. In a pre-recorded video message, actor Robert De Niro told the crowd in Minneapolis: “It is indeed a beautiful, hopeful day in the United States of America” as he urged them to prepare for further action. “Take a bow, but don't take a break, because today and everything that has gone before, is just a start, a rehearsal for the big show that's coming,” he said. “You know, the arrogant would-be king is absolutely scared to death about losing his power, and will do everything he can to hold on to it, without regard to reality, morality, humanity, nothing. We will face greater challenges down the road. For everything you've done, thank you, and now expect to be asked to do more. I know you will answer the call.”Ezra Levin, the co-founder of Indivisible, the progressive coalition behind the protests, called for a nationwide economic protest on May 1, urging supporters to skip work, school and shopping. “We’re going to show up and say we’re putting workers over billionaires and kings,” he said.Some Democrats echoed the sense of momentum. Senate Minority Leader Chuck Schumer wrote on social media that the protests were drawing “record turnout,” calling them “a very strong sign of what’s coming in November.”The White House, however, sought to dismiss the demonstrations. A spokeswoman said in a statement that “the only people who care about these Trump Derangement Therapy Sessions are the reporters who are paid to cover them,” echoing a line the administration has used to deride previous protests.