With flags fluttering at half-mast, the United States paused to mourn President John F. Kennedy and a generation's broken dreams, cut down 50 years ago by an assassin's bullet.
The young leader's brutal televised death, a dark turning point even in an era gripped by the Cold War nuclear stand-off and bloodshed in the jungles of Vietnam, shocked a global audience of millions.
Five decades on the wound is still raw, with many still obsessed by the conspiracy theories surrounding his death, and others gripped by regret for the America they imagine might have been.
Across the nation, at ceremonies large and small, many took comfort in reflecting upon the words of a charismatic man whose soaring rhetoric and call to service continues to inspire.
"Today, we honor his memory and celebrate his enduring imprint on American history," President Barack Obama declared.
Across the Atlantic too, Kennedy was remembered.
A wreath-laying ceremony was planned in the Berlin neighborhood where Kennedy gave his famed Cold War-era "Ich bin ein Berliner" speech to a rapturous crowd.
At Kennedy's tomb in Arlington Cemetery outside Washington, two kilted pipers from the Black Watch of the British army repeated a tribute their regiment had performed at his funeral 50 years ago.
In a proclamation ordering flags be lowered at government buildings and even private homes, Obama recalled Kennedy's leadership in the Cuban missile crisis, his speech in Berlin and his drive to advance the rights of African Americans and women.
"Today and in the decades to come, let us carry his legacy forward," Obama wrote Thursday.
"Let us face today's tests by beckoning the spirit he embodied - that fearless, resilient, uniquely American character that has always driven our Nation to defy the odds, write our own destiny, and make the world anew."
'Ask not what your country can do for you'
In Arlington, a steady stream of mourners visited Kennedy's grave, including his last remaining sibling Jean Kennedy Smith.
"It was a major shock to the world," said Tom Brown, 71, a retired civil servant. "Here we are, 50 years later, and we still remember. We still want to acknowledge him and his presidency."
Student Caitlin Coffey, 22, said she came down from Toronto specifically for the occasion.
"It's just remarkable to think that one person, one family, was able to make such a global difference," she told AFP.
Kennedy's voice still echoes through history to so many Americans.
"Ask not what your country can do for you; ask what you can do for your country," he urged Americans at his inaugural address on January 20, 1961.
Cut down in his first term at the age of 46 as he was driven through Dallas, Texas in an open-top limousine on November 22, 1963, Kennedy's unfulfilled promise has become a symbol of the lost nobility of politics.
He was a president who enlisted the nation in lofty goals - like putting a man on the Moon - "not because they are easy, but because they are hard."
The anniversary has sparked a prolonged period of national and media reflection on the unfinished tenure of the nation's 35th president, his tragedy-stricken family and the evocative period in the early 1960s when his political star illuminated the world.
He was the fourth US president to be killed in office, but the first whose death was caught on film.
The crime - and the image of blood splattered on the pink suit of his glamorous wife Jackie - stunned the world and traumatized the nation.
Many refuse to believe the killing could be the act of a single man: troubled Marine Corps veteran turned Soviet defector Lee Harvey Oswald, 26, who pointed a rifle out of a sixth floor window of the Texas School Book Depository and fired on the presidential motorcade.
Conspiracy theories continue to captivate doubters and fuel an industry of books, films and television specials.
A moment of silence was to be observed at Dealey Plaza and its infamous grassy knoll as Dallas marks the moment the shots rang out at 12:30 pm (1830 GMT) before celebrating Kennedy's legacy with music, prayer and speeches.
Carol Wilson, 68, was among the throngs of supporters who filled the streets of Dallas to welcome the dashing young president and his glamorous wife.
"We loved them," Wilson said as she described the joy she felt as Kennedy passed by on that day in 1963.
"I hope people realize we're not responsible," she told AFP as she waited for the memorial service to begin.
"I wish I could go back in time and change it."