Ethan looks a lot more excited before he swings his leg over the railing, before there’s nothing but a breeze between him and the river’s surface 20 feet below. At 10 years old, he’s the youngest of his crew—a gang of brothers and maybe cousins (but certainly no parents) out for an evening swim on the border of Glacier National Park. They’ve been here for hours. Most have already jumped. But the terror is fresh for Ethan.

“I’m nervous!” he shouts as his pack turns to goad him into the jump.

“Know what’ll help that?” his cousin calls. “If you jump.”

Ethan takes a deep breath. The sunset sparkles on the Middle Fork of the Flathead River below him. Sure, the river is deep here, but the Belton Bridge feels high when you’re planning to jump off it. There’s plenty of space under its concrete arch, enough for rafting tours to pass beneath and feel dwarfed by the bridge, slapping their paddles against the water to hear the echo. A group of gift shop employees has set up a barbecue under the decking, their backpacks resting on the concrete arch, hammocks slung between the piers.

Would living be worth it if it involved the shame of turning back? Ethan’s not sure. “Three!” he calls. “Two!” His knees bend. “One—”

The final number of his countdown ends in a groan as he turns his face from the river. His hands clasp the rail, knuckles white.

“It’s easy,” his brother yells from the riverbank.

Their cousin frowns between sips of his Corona. “Teegan, go do it with him,” he orders the nearest heckler. Without waiting for agreement, he shouts, “Teegan’s gonna do it with you!”

Ethan nods eagerly. “Teegan, we can die together!”

“I ain’t dying,” Teegan responds, pushing himself to his feet. In seconds he’s scrambled up the riverbank and onto the bridge. “Just don’t look down.”

“I kind of have to look down,” Ethan replies, casting a suspicious glance at the water sliding calmly below him.

The river, like the bridge above it, is calm today. You could almost join with the middle school boys in taunting Ethan (right up until they invited you to jump with them). While the Belton Bridge used to be the main entrance to the park, it closed in 1938, surrendering that duty to the New Bridge, as locals still call it, a quarter-mile downstream. The New Bridge starts rumbling with traffic an hour before dawn and sometimes hosts a traffic jam of people trying to get into the park. The Belton Bridge suffers no such crowds. It presides over the water like a grandpa in a rocking chair, watching the kids jump and maybe, if needed, springing into action.

The last time it was needed was nearly half a century before Ethan was born. In 1964, the Belton Bridge had been quietly fading for 26 years. Then, the worst flood in Montana history destroyed the New Bridge, cutting off access to the park and leaving tourists and employees stranded inside. Over the course of 36 hours, the area received as much as 14 inches of rain, which combined with snowmelt to flood the Middle Fork with 39 times the amount of incoming water that they would expect in a typical 50-year flood. Inside the park, tourists woke up in the middle of the night to find water lapping at the door of their RVs. A wall of water washed out the fireplace at Lake McDonald Lodge, leaving taxidermic animal heads poised on a chimney over a hole in the wall. Water poured into Lake McDonald from the Middle Fork despite the fact that it usually flows the opposite direction.

The economic impact for Montana was staggering. Nearly 20% of the state was impacted, with the damages totaling an estimated $62 million. On Highway 2, 20 miles of road were wiped out, along with sizeable chunks of the Great Northern Railway’s tracks. The park’s heavy road equipment, which would be critical for the cleanup effort, was parked 16 miles east of (and 3,000 feet above) Lake McDonald at Logan Pass, having just been used to clear the narrow Going to the Sun Road of snow.

And yet—

Within days of the flood, reports started to circulate, insisting that this crisis wasn’t unbeatable. Helicopters took men to the road equipment at Logan Pass. They drove it down to the rest of the park, clearing the famous Going to the Sun Road of mud and debris as they went. Another helicopter took a doctor throughout the park, inoculating people against typhoid as cleanup efforts began. Lodge employees busied themselves with work they never imagined would be part of their contract, like setting up a gift shop in a room with a missing wall. Ten days after the flood, the United States Secretary of the Interior visited the park and urged people across the nation not to cancel their plans to vacation there that summer.

Of course, if visitors were to come, they needed a way to get into the park. The New Bridge was a total loss and needed to be replaced. But a quarter-mile upstream, mostly ignored for the past two decades, sat the skeleton of the old Belton Bridge. The decking of the bridge had been swept away, but the concrete arch had endured. It was time to bring the old bridge out of retirement.

Within 15 days, park officials had laid a new trestle atop the dependable arch. For the next two years, the Belton Bridge once again served as the main entrance for the park until workers finished the New Bridge.

Today, a plaque stands next to the Belton Bridge to commemorate its history and service during the flood. While a strategically-placed row of boulders now blocks the bridge to motor vehicles, it’s still maintained as a footbridge and part of a bicycle path. As summer progresses and the normal swollen waters of spring recede, the riverbanks emerge to welcome picnickers like Ethan’s family and other people who seek a calm place to watch the water and air turn orange with the sunset.

“He’s not going to jump,” Teegan announces after emerging from the water. Despite all the countdowns, the encouragement and disparagement from the riverbank, despite even his vows to his brother that if Teegan would jump, he would jump, Ethan has still not let go of the railing for anything more than to tap a nervous beat on it.

“Ethan. Let—go—of—the—railing.” his cousin orders. “Just jump forward, and you’ll do great.”

“He’s shaking too much to jump,” another cousin says, loud enough that a cluster of teenage girls on the opposite bank can hear.

“My toes are tightening up for some reason!” Ethan shouts.

“Because they want you to jump! Come on, man, you’ve been up there for five minutes.”

“Is that all?”

His cousin turns away for a moment. Ethan takes a breath. His cousin turns back just in time to watch him arc through the air. A collective cheer instinctively rises from the riverbanks. People on both sides of the river leap to their feet, shouting and applauding. Ethan emerges from the water, takes a breath, and frog-kicks his way to the shore, grinning. The arch of the Belton Bridge smiles down on him.