When people think of American history of the mid-1800s, they usually think of the great westward expansion, the opening up of new territory, of covered wagons and the forging of the American frontier myth.

But, as historian David McCullough notes in the first chapter of his latest book: “Not all the pioneers went west.”

A lot went the other way, too, intent on opening up new territories of their minds. And many went to France.

So many were they, in fact, and so notable in their achievements, that they cried out for a book. Or two or three books. Mr. McCullough, a resident of West Tisbury, told his large audience at the Vineyard Haven Public Library on Sunday that the major problem in researching his new book on those Americans was deciding whom to leave out.

And so, the Pulitzer Prize-winning historian said, he felt like a movie casting director as he assembled his material. As if they would audition for him, “Tell me what they can do and show me a little bit about it.

“Then I decide whether they’re going to make the cut.”

The book on Americans in Paris is still a work in progress. Mr. McCullough is not even sure yet exactly when it will end. By which we don’t mean when he will finish writing — the book is due for release next year — but when the events within it will finish. He thinks probably around the start of World War I, in 1913 or 1914.

The start of the book, though, is more precise. It begins in the 1830s, because, as he said, the exodus of notable minds to Europe, which began at that time, has not been well covered by historians.

The people who are the subjects of his work, he noted, were not like those notables who had gone before, such as Benjamin Franklin, Thomas Jefferson or John Adams, who went to Europe in an official capacity.

These folks were not like that. They came from almost all the then-extant 24 U.S. states, but were not going in any diplomatic or official capacity. Only one among his subjects went with anything resembling paid employment.

They were mostly young, mostly single and in their twenties or thirties, mostly well-educated and well-off. Most knew little of life outside America; few knew anything much of France or the French language. Few had ever been to sea.

And, as Mr McCullough nicely put it: “Most of the people in the book do not yet know how important they are.”

“The focus of the book is about the Americans who went to Paris and the impact of that experience not just on them and their lives and careers professionally, but [what] that impact meant to our country,” said Mr. McCullough.

Like Oliver Wendell Holmes, to cite just one example. He was a moderately successful poet when he left for France at age 25, looking five years younger and just five feet three inches tall “when standing in a substantial pair of boots”

Mr. Holmes, the later giant (metaphorically) of the law, had then completed just one year of law school, and was contemplating a future as a doctor.

Others were a little older and more established, like the writer James Fenimore Cooper, Samuel F. B. Morse, educator Emma Willard. But they all had yet to make their greatest contributions to America.

In France they could immerse themselves in great culture, an opportunity still missing in America, and do it for free, as foreign students.

France was then considered the leading force in medicine. There was a blooming of art and literature. And the buildings! Rouen Cathedral was then several times bigger than any structure in this country.

To make the point, consider the complaint of one of the characters: that in America at that time there were no art schools, no drawing classes, few exhibitions.

Mr. McCullough did not delve deeply into the lives of his main characters during his fascinating presentation at the library. He only read the first chapter of his book.

What he offered was an introduction of the characters, an exposition on the vicissitudes of the time (an average sea voyage was four to six weeks long then, and immensely uncomfortable and dangerous), a scene setter, serving to establish what he called “one of the most important things” to convey about history.

And that is that “these people don’t know what the experience is going to do to them (or) to what they do with their lives.”

Nonetheless, that first chapter, packed with glorious McCullough detail, was gleaned, he said, mostly from sources located on this side of the Atlantic, in diaries, letters and memoirs.

He has been working on it for two years, and has never had a better time writing a book,” he said.

“The material,” he said, “is voluminous — a surplus of riches.”

It’s a safe bet that Mr. McCullough ensured himself a couple of hundred readers for when the whole book finally comes out next year.

Not that this was a marketing exercise. It was the first time, in his long career, that the historian has ever read from one of his books before publication, and it was done for the library, indeed as a plea for all libraries.

The program quoted him, and, for added emphasis, Myra Stark, president of the Friends of the Vineyard Haven Library, twice re-quoted him:

. “The greatest of all our American institutions is our system of public libraries. If you’ve tried to research or work with libraries overseas and abroad you are immediately reminded how fortunate we are.”

And before he began reading from the book, Mr. McCullough offered another plug for libraries and the need for people to help fund them.

“No other civilization, ever, has had anything comparable to our public library system,” he said.

“Free to the people. You walk through the portals of a public library and you’re walking through the portals to freedom. It’s important for all to remember the demands on them are greater than ever.

“And of course public funding for them is declining. So the rest of us have to make up for that.”

Most importantly, he said 65 to 70 per cent of the people using libraries nationwide, are children.

“So when the government cuts back on funding for libraries, they are cutting into children’s opportunities....” he said.

Still, things could be worse.

Said Mr. McCullough: “I’m sometimes reminded to tell people something that I take heart from, year after year. So, anytime you start to get a little down about the state of American society or the state of American culture, keep in mind that today, still, there are more public libraries in the United States than there are McDonalds.

“May it ever be so.”