President Donald Trump kicked off the nation’s 250th Independence Day celebration Friday with an address at Mount Rushmore that began by praising America’s exceptionalism before shifting to a politically charged message centered on what he described as the growing danger of communism.

“Communism is a mortal threat to American liberty,” he said from Mount Rushmore. “It is the greatest threat to our country, including World War I, World War II, Pearl Harbor or even 9/11.”

Although Trump has delivered similar remarks in recent speeches, the setting made this address particularly notable. Speaking at a national monument honoring four former U.S. presidents, his comments contrasted with the traditionally bipartisan and unifying Independence Day speeches previously delivered by presidents such as Gerald Ford and Ronald Reagan.

The president’s remarks also echoed themes associated with the anti-communist Red Scare of the 1950s, a period marked by investigations, blacklists and the persecution of individuals accused of communist ties in government, entertainment and other sectors.

Meanwhile, New York City Mayor Zohran Mamdani, a democratic socialist, delivered his own Independence Day speech, portraying the United States as a nation filled with contradictions while continuing to pursue its founding ideals “working each day towards the perfection in which it was conceived.”

Trump’s appearance concluded a holiday eve that was also dominated by an intense heat wave affecting much of the eastern United States. Officials urged those taking part in Fourth of July festivities to remain hydrated and seek relief in air-conditioned spaces when necessary.

Extreme temperatures forced changes to several holiday events. Philadelphia canceled its Salute to Independence parade, while Washington’s Great American State Fair temporarily closed during the afternoon before reopening later in the day. The Capitol Fourth concert ultimately proceeded with performances by Patti LaBelle, Trace Adkins and appearances by members of the Artemis II space mission, followed by fireworks over George Washington’s Mount Vernon. A separate Independence Day parade scheduled for Saturday in Washington was canceled.

By Friday afternoon, large crowds had gathered on the National Mall for the Great American State Fair. Visitors watched military flyovers, purchased food and drinks, and searched for shade while enduring sweltering conditions, many dressed in red, white and blue despite the oppressive heat.

Glenn Brooks, who received a presidential pardon from Trump for his role in the Jan. 6, 2021, Capitol attack, said he was “thankful to be participating in this grand event.”

The nationwide Independence Day celebration reaches its peak Saturday with fireworks displays, neighborhood gatherings and cookouts across the country. Trump is also scheduled to deliver another address on the National Mall before a fireworks display organizers describe as one of the largest in the nation’s history.

While much of the country endured dangerous heat, residents of the Pacific Northwest experienced far cooler weather, with temperatures in the 60s and occasional light rain.

In Seattle, soccer fans preparing for Monday’s World Cup matchup between the United States and Belgium enjoyed the mild conditions. Nearby in Issaquah, 31-year-old Megan Kurowski took her dogs to a local park before work and looked ahead to the evening’s festivities, including a possible paddleboard outing to watch the fireworks.

“Everyone’s just, from what it seems, been pretty excited about celebrating 250 years,” she said.

This year’s anniversary arrives during a period of deep political divisions, giving Americans both an opportunity to celebrate the nation’s history and reflect on the country’s current political climate.

Speaking in New York, Mamdani avoided mentioning Trump by name but appeared to challenge the president’s rhetoric during his address.

“For generation after generation, we have been told that when the world has sent its people to our shores, it has not sent its best,” Mamdani said in an apparent reference to a common criticism from Trump. “Those ideals upon which our nation was built, they are strong enough to endure any authoritarian regime, but only if we reach for them.”

The milestone celebration has also highlighted competing efforts to organize national events. Freedom 250, a group aligned with the White House, coordinated many of the festivities in Washington, while the bipartisan America250 commission organized celebrations in cities nationwide, including ceremonial ball drops and a concert in Los Angeles.

An April survey by The Associated Press-NORC Center for Public Affairs Research found that about four in ten American adults said they felt proud about the country’s 250th anniversary, while roughly three in ten described themselves as excited.

In Topeka, Kansas, auto technician Joe Fuqua-Bejarano reflected on what he believes defines the United States, saying resilience not politics is the country’s greatest strength.

“We’ve just all got to find unity somewhere, whether that’s in laughter or perseverance, and keep everybody cool,” he said from the fireworks stand where he is doing a booming business as a side hustle.

Christina Zhou, a 25-year-old research assistant from Cambridge, Massachusetts, said she planned to focus her attention on her local community during the holiday.

“It feels a little bit more like within our own personal control,” she said.

Jerry Chin of Newcastle, Washington, said he had not realized the country was marking its 250th anniversary and planned to spend the holiday quietly at home with his wife and their dogs, which become frightened by fireworks.

“America’s a great place, but there are some concerns,” he said.

Chin said healthcare and politics remain major worries for him and his wife.

“We’re Democrats, so kind of given up hope,” he said. “Just feel that it is the way it is. I don’t know if there could be change.”

At the National Archives in Washington, visitors toured the Rotunda to view the Declaration of Independence, the Constitution and the Bill of Rights while also escaping the extreme temperatures outside.

Among them was Michael Dresdner, 60, who traveled from West Orange, New Jersey, with his wife, Cindi, 57, and a group of roughly two dozen people to take part in the America 250 celebrations. He said the fact that members of the group represented different political viewpoints gave him optimism about the future of the country.

“We are all here, and we all love America,” he said.