BOSTON — Tens of thousands of demonstrators, emboldened and unnerved by the eruption of fatal violence in Virginia last weekend, surged into the nation’s streets and parks on Saturday to denounce racism, white supremacy and Nazism.

Demonstrations were boisterous but broadly peaceful, even as tension and worry coursed through protests from Boston Common, the nation’s oldest public park, to Hot Springs, Ark., and to the bridges that cross the Willamette River in Portland, Ore. Other rallies played out in Atlanta, Dallas, Houston, Memphis and New Orleans, among other cities.

The demonstrations — which drew 40,000 people in Boston alone, according to police estimates — came one week after a 32-year-old woman died amid clashes between white nationalists and counterprotesters in Charlottesville, Va., and they unfolded as the nation was again confronting questions about race, violence and the standing of Confederate symbols.

President Trump, who has faced unyielding — and bipartisan — criticism after saying that there was “blame on both sides” in Charlottesville, tweeted Saturday that he wanted “to applaud the many protestors in Boston who are speaking out against bigotry and hate. Our country will soon come together as one!”