BOSTON (AP) — John Howland may not be as famous as William Bradford, John Carver and Myles Standish, notable passengers on the Mayflower that landed in Massachusetts in 1620.

Yet Howland, who boarded the ship as Carver's servant, probably had a greater impact on the history of the United States than any of them. Hundreds of thousands of Americans will sit down for Thanksgiving dinner Thursday unaware that they owe their very existence to Howland, who almost never even made it to the New World.

Howland fell overboard in the middle of the Atlantic during a gale but grabbed a trailing rope and was hauled back aboard by sailors using boat hooks. His remarkable story is the subject of a new children's book, "The Boy Who Fell Off the Mayflower, or John Howland's Good Fortune," by Irish illustrator and author P.J. Lynch.

Howland and his wife, fellow Mayflower passenger Elizabeth Tilley, had 10 children and more than 80 grandchildren. Now, an estimated 2 million Americans can trace their roots to him.

Howland's descendants include three presidents — Franklin Roosevelt, George H.W. Bush and George W. Bush — as well as former vice presidential candidate Sarah Palin; poets Ralph Waldo Emerson and Henry Wadsworth Longfellow; actors Alec Baldwin, Humphrey Bogart, and Christopher Lloyd; Mormon church founder Joseph Smith; and child care guru Dr. Benjamin Spock.

"The idea that the existence of all these people hinged on that one guy grabbing a rope in the ocean and holding on tight totally caught my imagination," Lynch said in a phone interview from his Dublin home. "Many of these people have made America what it is."

There are so many Howland descendants that they have their own club — The Pilgrim John Howland Society — with about 1,200 members.

Gail Adams, a Howland descendant and editor of the society's publication, "The Howland Quarterly," was thrilled when she first found out about her lineage two decades ago.

"To think, if he hadn't made it, I wouldn't even be here," she said from her home in Virginia.

Lynch developed an interest in the story of the Pilgrims and Howland when he read Nathaniel Philbrick's book, "Mayflower." It was mostly new to him because he hadn't gone to school in the U.S., where the story of the Pilgrims is taught to every child.

He acknowledges his book — written in the first person from Howland's point of view — isn't a 100 percent accurate account, and he has taken some liberties in telling and illustrating the story. For example, Howland was actually a young man on the Mayflower trip, not a boy as the book title suggests.

But that's OK with the experts — and Howland's very large extended family.

"He did a great job on it," said Richard Pickering, deputy executive director of Plimoth Plantation, the living history museum in Plymouth, Massachusetts, that preserves the story of the Pilgrims. "There is very little documentation about Howland's early years, but Lynch imagines them beautifully."

"He's right on," Adams said.

The book even describes the beginnings of a romance between Howland and Tilley, which isn't so farfetched, Adams said.

Tilley was left an orphan after the first winter in Plymouth yet chose to stay even though she had family in England and her best friend returned.

"My theory — no proof — is that when handsome John fell overboard and had to be nursed back to health, she was smitten," Adams said.