GEOFF BENNETT: With the 250th birthday in sight, the Crossroads team is examining what it means to be an American and reflect on what the founders built, who they left out, and what in that 250-year history has been left unresolved.

Judy Woodruff traveled to Vermont, a state with the motto Freedom and Unity, to try to get answers to these questions for her series America at a Crossroads.

JUDY WOODRUFF: Dishes clatter, booths are cramped, and orders fly out of the kitchen.

It's lunchtime at the Country Girl Diner in Chester, Vermont, where the service is brisk and the answers to my questions are thoughtful.

What does it mean to people to be an American?

SCOTT MACDONALD, Vermont Resident: Seeing my country essentially split in half is very, very painful.

JUDY WOODRUFF: For customer Scott MacDonald, the country's bitter political divide is front of mind.

SCOTT MACDONALD: There was a time when you could just quietly disagree with somebody, and that seems to be gone.

JUDY WOODRUFF: Teacher Wendy Hayward told me understanding our past starts with how it's presented.

WENDY HAYWARD, Vermont Resident: The way we have taught history in this country has been an avoidance of what our history is.

JUDY WOODRUFF: The ideas here point to a deeper question, what kind of a country did the founders build, and who did they leave out?

WENDY HAYWARD: What really happened with slavery?

What really happened with minorities, women?

JOSEPH ELLIS, Author, "The Great Contradiction: The Tragic Side of the American Founding": I wanted to be able to go back to the founding.

JUDY WOODRUFF: I met Pulitzer Prize-winning surprise winning author and historian Joseph Ellis at the Echo Lake Inn in nearby Ludlow, Vermont, built shortly after the American Revolution.

JOSEPH ELLIS: This is G.W.

to Joseph Reed December 12, 1778.

JUDY WOODRUFF: He's spent much of his life reading primary documents written by Washington, Jefferson and other founding fathers.

JOSEPH ELLIS: You got to have one idea for one page.

JUDY WOODRUFF: Taking meticulous notes for his books, all written by hand.

JOSEPH ELLIS: We must acknowledge that all of these people were human beings.

They weren't gods.

JUDY WOODRUFF: In his latest book, "The Great Contradiction: The Tragic Side of the American Founding," Ellis acknowledges the founders were trying to do something that had never been done before.

JOSEPH ELLIS: It reversed the tectonic plates of Western political thought.

Power did not flow downward from God to kings, but upward from that mysterious crew called the people to their elected representatives.

JUDY WOODRUFF: But he says a fatal flaw was in how majority will was designed and who was included or excluded from participation.

Ellis adds, when it came to race, the majority of colonialists drew a line.

JOSEPH ELLIS: If you say, do you want to end slavery, they will say yes.

Then do you want a biracial society?

No.

All whites, all of them in the North and the South say the same thing.

JUDY WOODRUFF: By 1776, one in five people in the American colonies were enslaved.

And Native nations controlled most of the land west of the Appalachians.

Yet neither group was included in the Constitution and its promise of we, the people.

JOSEPH ELLIS: Even those that are very much in favor of ending slavery are not in favor of granting them equal treatment at all.

The failure to end slavery means in the end the Civil War is inevitable.

JUDY WOODRUFF: That war that began nearly eight decades after the country's founding left over 600,000 Americans dead and left us as a nation grappling with the same moral question for generations to come, from President John F. Kennedy... JOHN F. KENNEDY, Former President of the United States: The heart of the question is whether all Americans are to be afforded equal rights and equal opportunities.

JUDY WOODRUFF: ... to President George W. Bush... GEORGE W. BUSH, Former President of the United States: Slavery is a blight on our history, and that racism, despite all the progress, still exists today.

JUDY WOODRUFF: ... and President Barack Obama.

BARACK OBAMA, Former President of the United States: Race remains a potent and often divisive force in our society.

JUDY WOODRUFF: And it continues today, as the Trump administration tries to reshape how race is taught and remembered.

(CHANTING) JUDY WOODRUFF: Debates over policing, voting rights and federal power also continue today, including in Minnesota, where federal actions and protests have raised new questions about whom the law protects.

Ellis says the founders postponed a decision on slavery because they feared it would destroy any chance of a new nation before it even came into being.

JOSEPH ELLIS: If they raise the issue during the war, the South will secede and will lose the war.

And if we raise it during the Constitutional Convention, the same thing.

It will never pass.

JUDY WOODRUFF: Ellis contends the second major failure was the exclusion of Native Americans, who were not citizens, had no vote, and were not considered in the treaty that formally declared the United States a nation at the end of the Revolutionary War.

JOSEPH ELLIS: They basically confiscated all their property, claiming they lost the war or something.

They didn't lose the war.

One of the things that propels me towards a more positive view of Washington is that Washington, as president, he's very busy, and his secretary of war comes to him and says, unless we do something, we're on a path that the only Native Americans east of the Mississippi will be in history books.

Your whole future as a distinguished American president will depend upon you getting this right.

JUDY WOODRUFF: Yet, over the next century, the United States signed more than 370 treaties with tribal nations and broke nearly every one of them.

Ellis said George Washington in particular was aware the failures and the founding documents would haunt him.

JOSEPH ELLIS: If you want to understand this chapter in American history, the greatest generation of political leaders in American history did unbelievably large things that we're celebrating right now, and they failed.

And guess what?

Of all of them, Washington knew it the most.

JUDY WOODRUFF: He understood the contradiction the most.

JOSEPH ELLIS: He understood the contradiction.

And he knew that, if his reputation was linked to slavery, it would do him enormous damage.

JUDY WOODRUFF: He also stresses the founding documents aren't written in stone.

JOSEPH ELLIS: The Constitution itself isn't a set of truths.

It's a framework in which we continue to argue about what the truths are.

We have lost that capacity, it seems to me, to argue with each other in a strenuous but friendly way.

JUDY WOODRUFF: And, ever the college professor, Ellis gave each of us an assignment.

JOSEPH ELLIS: Read the Declaration.

It's only two pages' long.

You can pull it up on your cell phone, OK?

JUDY WOODRUFF: Right.

JOSEPH ELLIS: The second is, read a book called "Common Sense."

JUDY WOODRUFF: Thomas Paine.

JOSEPH ELLIS: Thomas Paine.

It's the single most influential book in shaping the way in which American history goes.

WENDY HAYWARD: You don't change history.

History is what it is.

JUDY WOODRUFF: Back at the Country Girl Diner, the weight of that history is still in the air.

WENDY HAYWARD: We have to learn from it.

We have to live it.

And if we want to change, we have that ability.

JUDY WOODRUFF: Including the ugly - - the good, the bad and the ugly.

WENDY HAYWARD: The good, the bad and the ugly.

SCOTT MACDONALD: We have had parts of our history that are shameful, of course, and every country has.

It's what we do about it now that matters.

JUDY WOODRUFF: For Joe Ellis, the historian, the nation's future is what he's most concerned about.

JOSEPH ELLIS: This is the most important midterm election in American history.

The republic is on the ballot.

I can understand which side of the coin you're on, but I cannot understand if you're indifferent.

Whatever position you end up concluding is yours, act on it.

JUDY WOODRUFF: For the "PBS News Hour," I'm Judy Woodruff in Ludlow, Vermont.