We are riding the hop-on, hop-off bus through Philadelphia. Two complete circuits.

On the first, we skip the stop at the Betsy Ross House.

“Who is Betsy Ross?” we ask each other.

On the second circuit, we get off. Not least because the courtyard looks like a pleasant museum café. There is no café, as it turns out, just a lovely spot and takeaway drinks. We stay anyway.

We are still wondering: who was Betsy Ross? And why does she have a museum of her own in Philadelphia, of all places — the city where the young republic took political shape, among Independence Hall, the Liberty Bell and Benjamin Franklin?

The house is small. Narrow stairs, low rooms, creaking floors. Upstairs, a woman in period costume sits sewing. Beside her lies an American flag with thirteen stars arranged in a circle. For an American, the image is immediately recognisable: a woman, a needle, a piece of cloth — and the birth of a national symbol.

As we leave the museum, we notice two words on a wall: “Be Brave”.

Only outside, with our drinks, do we really begin to explore the story of Betsy Ross.

It goes something like this:

In 1776, George Washington is said to have visited Betsy Ross at her house with two other men. They probably knew each other. Ross was an upholsterer and also made flags. Washington showed her a design for a new banner. She is said to have suggested changes, demonstrated a five-pointed star with a single snip of the scissors and finally sewn the first American flag.

A perfect story. But perhaps not the whole truth. Or not quite the truth.

There is no contemporary evidence for it. The story only became known decades later through Betsy Ross’s family. In the late nineteenth century, paintings, prints, textbooks and patriotic education spread the image of the young woman sewing the first flag under George Washington’s gaze.

What is historically established is that Ross worked as an upholsterer and was one of several women in Philadelphia who made flags during and after the Revolution. Whether she was the one who sewed the first cannot be proved.

The museum does not hide this uncertainty. And yet, upstairs, the woman in costume sits sewing.

That is not a contradiction. Perhaps it is the very heart of the story. Because in America, Betsy Ross is not simply a historical person. She is a figure in the nation’s memory. A name American children know.

Like Paul Revere.

A few days later, we will encounter him in Boston — and, everywhere, a famous line from Henry Wadsworth Longfellow’s poem: “One if by land, and two if by sea”. It refers to the lanterns in the steeple of the Old North Church. One lantern was to signal that British troops were approaching overland; two, that they were coming across the Charles River.

This story too has everything a good national narrative needs: night, danger, a secret signal, a rider and a country on the brink of revolution.

Paul Revere really did ride out to warn of the British troops. But he was not the only rider. Dozens of people spread the alarm that night. Revere became a solitary hero largely through Longfellow’s poem, published almost a hundred years later, which turned a complicated collective effort into a clear story with a single name.

Betsy Ross and Paul Revere. Two names almost every child in America knows, and which initially mean nothing to us.

Perhaps this is part of the difficulty of understanding America from the outside. We know the great milestones: the Declaration of Independence, the Revolution, the Constitution, presidents, wars. But we do not necessarily know the small stories through which that history is passed on.

The seamstress with the flag.

The rider in the night.

The rock at Plymouth where, according to tradition, the Pilgrims came ashore.

Such stories are manageable. They have a plot, a clear image and usually a hero or heroine. You can tell them, paint them, print them in schoolbooks, perform them in museums and pass them from generation to generation. And ultimately, they are about more than writing history. They are about how America sees itself. Or would like to see itself. In that sense, whether every detail of a story can be substantiated becomes beside the point.

The stories of Betsy Ross and Paul Revere are not only about the question: what happened? They are also about which stories a country wants to remember, and what those stories are meant to say about the country and its citizens.

Betsy Ross is a remarkable heroine in that respect. Not a president, not a general, not a great orator, but a craftswoman. A woman who makes something. Perhaps that also explains the success of her story: the founding of a nation can be told through the small, understandable act of sewing.

Philadelphia is full of such figures.

Benjamin Franklin is historically hard to overlook: printer, inventor, diplomat, statesman — a man with almost too many roles for a single biography.

And then there is Rocky.

A figure who never lived and yet ranks among the city’s best-known sons. People run up his steps, raise their arms at the top and have their photographs taken beside his statue. The fictional boxer has long since become a public symbol of Philadelphia.

Franklin. Betsy Ross. Rocky.

When we leave the Betsy Ross House, we do not know whether she really sewed the first American flag. But we understand a little better why America wants her to have done so.

And then there are those two words on the wall: “Be Brave”.

They fit. Because the story of Betsy Ross does not merely describe America as it supposedly was. It also reminds it of what it wants to be: brave, inventive, independent — and willing to piece something new together from a few separate scraps.