Updated at 5:52 p.m. ET

Four hundred lights around the Lincoln Memorial's reflecting pool were lit Tuesday evening to honor the 400,000 people in the U.S. who have died from COVID-19.

President-elect Joe Biden and Vice President-elect Kamala Harris both spoke.

Other cities across the country are making their own tributes to those lost to COVID-19 on Tuesday. The Empire State Building in New York and the Space Needle in Seattle are among the buildings being lit.

In September, volunteers placed 20,000 flags on the National Mall when the death toll crossed 200,000. Other memorials have popped up around the country, from roadside drive-bys to people's front lawns.

But the reflecting pool ceremony, hosted by the incoming president, is the most prominent effort so far to remember those who have died.

"This is an iconic vista of heroes and honor and of memorialization," says history professor Micki McElya, who wrote the book The Politics of Mourning: Death and Honor in Arlington National Cemetery. "It's impossible to consider that terrain without also thinking of the March on Washington for Jobs and Freedom in 1963."

The memorial, building upon prior localized efforts, represents the "realization of the work of a lot of people and the realization of the need to come together and honor those who've been lost, but also to reckon with those losses and what this means for this country," McElya says.

McElya talked with NPR's Mary Louise Kelly on All Things Considered about collective mourning during a pandemic when people continue to die. Here are excerpts, which include Web-only extended answers:

You wrote about how sharing grief brings people together, and I wonder if you would elaborate on that.

Sharing grief brings people together, especially in the United States, like nothing else. This is a vast country of an enormous and varied population. Most Americans will never know one another personally, see one another. Yet it's in moments of national mourning, it's in moments of collective grief and collective honor that we come together, that we experience those bonds of nationhood and community across all of these many different lines of difference. Often lines of difference that, of course, we understand all too well are fraught and violent and difficult.

And there can be no unity, there can be no collectivity without a shared sense of of belonging, without a shared sense of community in this nation. And that's what collective grief offers.

I wonder whether it is harder to mourn while we're still in the middle of something.

It is difficult to imagine a permanent memorial at this point, something that we will need and something that people are working toward because these devastating losses continue. ... Yet I believe that it's more important now than ever ... to honor those who have died, but also to enact collective mourning, in part to maintain vigilance, in part to remind us how important it remains and is to wear masks, to follow public health recommendations, that this is a collective effort that has to continue. And it's important to recognize the losses already and the terrible costs that we've paid already that have been borne disproportionately by different communities in this country. There's no way that we can build from this and repair so much of the damage without a clear-eyed, honest, sober confrontation of what's happened. This is the reckoning that we need.

It's worth noting that we mark this moment of 400,000 lives lost in the U.S. at a moment when our capital city is locked down, is militarized in the service of protecting Americans from other Americans. How does that complicate collective mourning?

It is both an enormous barrier and makes the stakes that much higher. ...

One of the things that has really struck me is that for the inauguration tomorrow, there have been thousands of American flags placed along the Mall to represent the people who would have been there, the people who can't be there because they can't safely gather in that space.

The space that is about speaking back to the nation and about representing the nation is itself not only militarized and locked down, but an unsafe environment for public health.

Just a few months ago, there were thousands of flags there marking the dead. And the toll at that point was 220,000. We already have lost so many more people. It is confronting that.

And I do believe that these are moments that can help heal. And not in a naive way, but in a profound and true way.

Kat Lonsdorf and Christopher Intagliata produced and edited the audio interview. James Doubek produced for the Web.

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