Basking Ridge, N.J., is contemplating how to let go of the white oak tree, now in failing health, that has stood in its midst for more than 600 years. (Yana Paskova/For The Washington Post)

Well before Columbus sailed to the New World and even before Gutenberg invented the printing press, there grew a great oak tree in a land that would one day be called New Jersey.

The oak was already old when farmers built a church beside it in 1717. And when the people came and kept coming, a town called Basking Ridge was built around the church that was built beside the tree.

Town and tree would always be inseparable, or so the people thought.

In 1740, English evangelists James Davenport and George Whitefield preached beneath the tree, spreading the word of the “Great Awakening” to more than 3,000 people. George Washington’s troops drilled on the village green in view of the ancient oak, and the general picnicked beneath it with his friend the Marquis de Lafayette. On his way to the Battle of Yorktown, Gen. Jean-Baptiste Rochambeau marched 5,500 French soldiers past the oak and into history — and soon after the tree shaded the graves of 35 veterans of the revolution.

Through war and natural disaster and a thousand storms or more, the tree survived. In the 1920s, four men scooped out part of its rotted trunk and then stood inside it, amazed at its girth, before pouring concrete into the cavity to save the oak. They also added cables and “crutches” to ease the weight of the branches grown longer than the tree was tall.

Under the sprawling branches of the historic “Holy Oak” in Basking Ridge, N.J., a plaque notes the tree’s dimensions half a century ago. (Yana Paskova/For The Washington Post)

And when drought parched the community in the 1970s, residents didn’t mind when volunteer firefighters slaked the oak’s thirst. “And if at any time, we have another drought and people are told they can’t water their lawns, they can’t fill their swimming pools, there will always be water for this tree,” a town historian said years later.

But what if, eventually, all the tender loving care isn’t enough? A couple of springs ago, people noticed that the tree was less green in the top of its canopy and its gray denuded branches seemed to scold the sky. They worried over what was happening to their beloved oak — the oldest white oak in the country and perhaps the world. Scientists were called in, plans were offered up, and everyone waited to see what the next spring would bring.

“We had great hopes,” said Dennis Jones, the pastor at Basking Ridge Presbyterian Church. “All eyes were on the tree to see how it would green.”

When it didn’t last month, when even more of its upper branches stayed bare, other experts were consulted. They tested the soil, probed the tree’s roots, checked for beetles and disease. Jason Grabosky, an ecologist at Rutgers University, inspected the tree in mid-June and declared it, after more than 600 years, to be “in a spiral of decline.”

Although Grabosky gave no timeline, residents are suddenly preparing for the worst. Many talk about the tree’s demise as they would a family member’s. “It’s about knowing when to let go,” Jones said.

The tree still stands close to 100 feet tall, and its branches extend more than 130 feet side to side. It anchors the north end of the center of Basking Ridge, a postcard-perfect town about 40 miles west of New York City. It’s a place where no one pays for parking on the main streets, where locals are used to greeting tourists who’ve come from all over the country specifically to marvel at the age and stamina of the town’s most famous occupant.

Of course, there have been other great oaks: The Charter Oak, in Hartford, Conn., was 500 to 600 years old when it fell in a storm in 1856. The Wye Oak, in Wye Mills, Md., was 450 years old when it suffered a similar fate in 2002.

But the Holy Oak, as Basking Ridge’s tree is often called, kept going. It was struck more than once by lightning. It was blasted by Hurricanes Diane, Donna and Dora, then Floyd, Irene and Sandy. Through tornadoes and derechos, blizzards and floods, it buckled and bent. It swayed and swooned. But it never succumbed.

The tree’s sudden failure to thrive is a mystery. Pastor Jones thinks the reason could simply be old age. White oaks usually live between 200 and 300 years. The Basking Ridge oak has surpassed that by several centuries.

No one really knows how or why trees die. Scientists know how they grow, and they know how to reconstruct their past. But they don’t know how to predict their future — except to say that the warmer the planet becomes, the more trees will die.

“Because trees live longer, we tend to view them as timeless,” U.S. Geological Survey ecologist Craig Allen told High Country News two years ago. “You can feel this sense of endurance. In human terms, we would call it wisdom.”

Such wisdom is gained by understanding the past, which trees do right down to their roots, “because they’re tuned to that historic climate window,” Allen said. “They know there are ups and downs in water and sun, and they know how to ride them out, except that it’s become vastly harder in the age of global warming.”

The white oak casts a large shadow in Basking Ridge. Many features of the community of nearly 29,000 honor it, from Oak Street Elementary to the Ridge Oak Senior Housing complex, where the monthly newsletter is called “Acorns.” Every year at the Presbyterian church’s “Tree House” preschool, children spend six weeks studying trees, and a local arborist is invited to tell them the old oak’s story.

“This is a really big deal for the kids,” said Carol Hipsher, a native who has taught here since 2011. On Thursday, she was escorting her brother and brother-in-law around the grounds when they stopped to take a photo. “You don’t know when it won’t be here anymore,” she said.

Residents worry about the inevitable, but they also worry about doing the right thing. Cutting away even more dead limbs may not be the answer, Jones said. “We want to treat the tree with respect,” he said, “and not prolong its death.”

Bill Emmitt, the church trustee in charge of the tree, hopes they won’t have to let go too soon. “Based on the advice we’ve received,” he said Wednesday evening, “there’s enough life in the tree, and the upper part of the tree is strong, so that even though it doesn’t have leaves on it, [the arborists] think with tender loving care it can continue” — at least “for the foreseeable future.”

It would, indeed, be a blessing. “This is personal for us,” said Ruth Bashe, a longtime church member. “Every time a minister leaves, he says, ‘Whew, the tree didn’t die on my watch.’ ”

Emmitt even holds out hope that once the canopy is inspected, the experts may find “dormant buds” that would indicate some branches could bear leaves again. “We’ve got some good people working on it,” he said. “We’re hoping that with a combination of things, we can have, maybe not a return to the past, but hopefully just keep the old girl going for a while longer.”

If not, the tree might need to come down as soon as next year. There may be some consolation, though, in an enterprise a congregant thought up about 10 years ago. Money was needed at the time to renovate the cemetery, and so acorns from the tree were collected and 100 saplings grown at a local college. The oak tree’s progeny were then sold to the public for $100 each.

With word of the tree’s ill health spreading, the church’s phone has been ringing. At least a dozen calls have come from people who bought the saplings a decade ago. Planted in yards around New Jersey, those babies are five to 10 feet tall now, and their owners have offered them up to take the place of the “great one,” if it comes to that.

“There is a life eternal,” Emmitt said, “and all these new trees are a testament to that.”