President Joe Biden has addressed the nation as the US marks 500,000 deaths from Covid-19, the highest toll of any country in the world.
"As a nation, we can't accept such a cruel fate. We have to resist becoming numb to the sorrow," he said.
The president and vice-president, and their spouses, then observed a moment of silence outside the White House during a candle-lighting ceremony.
More than 28.1 million Americans have been infected - another global record.
"Today I ask all Americans to remember. Remember those we lost and remember those we left behind," President Biden said, calling for Americans to fight Covid together.
How did Biden mark the occasion?
Mr Biden ordered all flags on federal property to be lowered to half mast for the next five days.
At the White House, he opened his speech by noting that the number of American deaths from Covid was higher than the death toll from World War One, World War Two, and the Vietnam War combined.
What 500,000 US deaths look like
"Today we mark a truly grim, heartbreaking milestone - 500,071 dead," he said.
"We often hear people described as ordinary Americans," he went on to say. "There's no such thing, there's nothing ordinary about them. The people we lost were extraordinary. They span generations. Born in America, emigrated to America."
"So many of them took their final breath alone in America," he continued.
He drew on his own experience with grief - his wife and daughter were killed in a car crash in 1972 and one of his sons died from brain cancer in 2015.
"For me, the way through sorrow and grief is to find purpose," he said.
Mr Biden's approach to the pandemic is different to his predecessor Donald Trump, who cast doubt on the impact of the deadly virus and was viewed as having politicised the wearing of masks and other measures to prevent the spread of the virus.
On 19 January, one day before Mr Biden took office, he held an event to mark 400,000 Americans dying of the disease.
Monday's event, marking the latest death toll, comes about one month later.
Elsewhere in Washington, the bells at the National Cathedral tolled 500 times, once for every thousand Americans lost during the pandemic.
Source: BBC News
BDST: 1225 HRS, FEB 23, 2021