AMNA NAWAZ: Many Americans feel we're living through an extraordinarily divided time, but historian Heather Cox Richardson says there is precedent, both for our conflicts today and for the hope that we can overcome them.

Judy Woodruff recently sat down with Richardson for her ongoing series America at a Crossroads.

HEATHER COX RICHARDSON, Author, "Democracy Awakening: Notes on the State of America": And he really went out of his way to work with people across the aisle.

His Cabinet was made up of his rivals.

JUDY WOODRUFF: At the Lincoln Cottage in Washington, D.C., a museum that once served as the residence of the president who presided over the country during its greatest test, the Civil War, I met Heather Cox Richardson.

HEATHER COX RICHARDSON: He was trying to preserve the Constitution.

JUDY WOODRUFF: She's a historian at Boston College who in recent years has become known to many more as the author behind her daily Substack newsletter "Letters From an American," where she analyzes today's events in the context of our past, drawing parallels to find guidance forward.

Her new book, "Democracy Awakening: Notes on the State of America," explores other divisive periods in American history and how remarkable individuals help prevent its fall to authoritarianism.

The book opens with a familiar diagnosis of our present: "America is at a crossroads."

HEATHER COX RICHARDSON: We're in a moment in which we are facing a choice between preserving and expanding American democracy, the idea that everybody should have a right to be treated equally before the law and to have a say in their government, on the one hand, and, on the other hand, the idea of authoritarianism, which is rising in the United States, as well as around the world.

This is the moment when we choose between those two things.

And so this is a moment when we're standing at a crossroads.

JUDY WOODRUFF: People are asking me often, how long has this polarization, this division been around In our country?

You're a historian.

You have studied this.

How deep were the divisions at the very beginning of this country?

HEATHER COX RICHARDSON: We have, in fact, always been divided.

The question is whether that division dominates our politics or not.

So, yes, of course, there were divisions at the beginning of this country, both within those people who ruled, but also between the people who ruled and the people who didn't have a say in their government, who didn't have any rights, women, indigenous Americans, Black Americans, brown Americans.

So those sorts of divisions have always been in our society.

What makes this moment different and what makes it look like more divided times in our history, like the 1850s, for example, or the 1890s, or the 1920s, is that those divisions are playing out in our politics.

And for the first time in our history, a major political party has been taken over by a small faction that does not believe in democracy.

JUDY WOODRUFF: But when it comes to the treatment of people of color, of Blacks, of people who are immigrants, that's something this country has wrestled with from the very beginning.

Why has that been so hard?

HEATHER COX RICHARDSON: Well, that indeed is the heart of where American life began, with these conflicts between different groups of people, especially between those people who monopolized politics, wealth, and society and the people who worked for them, essentially, or who were enslaved by them, or who were simply not considered human beings.

So, the idea that everybody should have a say takes a very long time to develop, and it is very much in our DNA in this country.

I would like to say, though, that in a way that has also been our inoculation in the past against authoritarianism, because those people who were marginalized always kept in front of everyone the aspirations of the Declaration of Independence.

So, while, in fact, Black Americans and indigenous Americans were excluded from the Constitution, were in the minds of the founders excluded from the Declaration of Independence people of color from the beginning talked about, hey, wait a minute, those are great principles.

Why don't they apply to me?

Why don't they apply to us?

We feel the same way.

And by continually holding up those standards and calling people to account when they were not meeting them, I think they have really helped the United States continually to expand the idea of democracy, to expand the idea of who's included, and to create a more just society.

JUDY WOODRUFF: So there's a persistence there.

I mean, over time, marginalized groups have made this argument again and again and again, as you say, kept it in the forefront of our consciousness.

Where did that resilience come from?

How do you explain that?

HEATHER COX RICHARDSON: One of the great brilliances of Abraham Lincoln was to rededicate the nation not to the Constitution, which was the document that enslavers rested on because of its protection of property.

It's kind of a truism in American history, if you have rights, you look to the Constitution.

If you want rights, you look to the Declaration.

And Abraham Lincoln relying on the Declaration of Independence as the heart of the United States.

Four score and seven years ago, our fathers brought forth on this continent a new nation conceived in liberty and dedicated to the proposition that all men are created equal.

He's pointing to the Declaration, not to the Constitution.

And having those principles be central to the foundation of this nation makes it easier, I think, for people who don't have rights to say, I'm not doing anything radical here, the same way that Lincoln did.

He said, I'm not doing anything radical when I talk about human freedom.

I'm relying on our foundational document.

JUDY WOODRUFF: Are there elements of the 1850s that are with us today?

HEATHER COX RICHARDSON: Yes, the good ones, as well as the bad ones.

So, the divisions in our country that are created by politicians who are garnering power and amassing wealth by limiting our access to media, for example, so that people get into their own silos, by demonizing the other in our society, something that the elite enslavers did with great success, the people who are taking over the key nodes of our democracy, the Supreme Court, the Senate, those things also happened in the 1850s.

So you can see a march that looks much like the 1850s in the negative aspects of our lives.

By 1856, Northerners have woken up and said, hey, listen, we disagree about immigration and finance and transportation and internal improvements, but we can agree we don't want that.

By 1856, they have put together a political party to push back against that.

By 1859, Abraham Lincoln has articulated a new concept of democracy that calls for a government that serves ordinary individuals, rather than the elite enslavers.

By 1860 voters, all white men of property, have elected him to the White House.

By 1861, he has signed the Emancipation Proclamation, ending the idea of human enslavement as the foundational principle of this nation.

And, by 1863, he has given the Gettysburg Address, rededicating this nation to a new birth of freedom based on the Declaration of Independence.

That idea of ordinary people waking up and finding the leaders who will articulate those principles is as alive today as the bad side of the 1850s is alive as well.

JUDY WOODRUFF: We have talked about difficult, very difficult times leading up to the Great Depression.

That was a period when there were strong authoritarian voices on the left and on the right.

Other countries around the world succumbed to some of those forces, as we know, in that period.

But this country didn't.

Why not?

HEATHER COX RICHARDSON: I actually think the real reason is simply because the United States had such a strong tradition of marginalized communities insisting on equality before the law and recognizing the dangers of authoritarianism.

We tend to hail Franklin Delano Roosevelt as a great hero, which, of course, in many ways he was.

But it's worth remembering that he was articulating a vision that had been put forward by other Americans like Frances Perkins, who was going to become his secretary of labor and who herself recognized the extraordinary need of a government that answered to the people, because she had witnessed the Triangle Shirtwaist fire, in which girls and young workers had been locked into a factory that caught fire and jumped out the windows to their deaths.

And she said in a memoir much later that she would never forget the sound of bodies hitting the sidewalk, and that she dedicated her life to making sure that governments would protect people who couldn't protect themselves.

JUDY WOODRUFF: Some people are talking very much about the rise of antidemocratic forces in this country, worrying that we could be headed for something like another Civil War.

But you're saying you see more hope than you do darkness.

HEATHER COX RICHARDSON: I see us walking on a knife edge.

We absolutely could go that direction.

And we know full well that there are leaders in this country who have advocated doing that.

I mean, one of the things that worries me a lot is that, since 2015, there tends to be an in an attempt to pretend that the things that people like former President Donald Trump are saying are simply window dressing, when he is literally talking about calling the former chair of the Joint Chiefs of Staff somebody who looks like he has committed treason and then suggesting that the punishment for treason should be death.

That is an extraordinary statement.

It is a statement that, in any period before 2015, would have ended a political career, would have been Headline News for weeks.

And it barely made the front pages.

So, that idea of the rise of authoritarianism, the idea that our population is so destabilized and so angry that it would reach for an authoritarian who promised to return to a perfect past is very much on the table.

But it is not inevitable.

The future is never inevitable.

JUDY WOODRUFF: When it comes to authoritarianism, you look around the world, we see what's going on in India and Turkey.

And yet you're also writing these days that you have hope for the future.

So where does that hope come from?

HEATHER COX RICHARDSON: Well, the hope is in us.

I mean, the whole point of democracy is that we get to have a say in our futures.

We get to be treated equally before the laws and we get to say who governs us.

And I really believe in American democracy.

We have been through extraordinarily hard times before.

I smile a little bit when people say, is this the worst ever?

I'm like, well, tell me which were the good years.

Tell me which -- what was the year that things were really good?

Was it 1923?

No, that one wasn't so good.

We have always had hard times.

And, until now, we have always, at the end of the day, done the right thing.

I'm very worried in the short term.

But I have faith in American democracy, and I have faith in humanity.

So -- so, yes, I have hope.

But it's going to be a lot of work.

JUDY WOODRUFF: For the "PBS NewsHour," I'm Judy Woodruff in Washington.