FLEMING-NEON, Ky. — This sliver of land wedged between the thick woods and Wright Fork creek has been the home of Gary Moore’s family for as long as there has been a United States. The burial plot for an ancestor who fought in the Revolutionary War, he said, is a mile away. Mr. Moore himself lives in a mobile home across from his father’s house; the house where his grandmother lived is next door.

All of that was wrecked in last week’s flooding.

“This is kind of like the final straw,” Mr. Moore, 50, said as he looked out at a new terrain of shredded homes, crushed cars and endless debris. “We’re gradually losing it — that bond we had. It’s slipping away. People are getting out of here, trying to get better jobs and live better lives. I’m leaning in that direction myself.”

For much of the last century, the country was powered by the labor of coal miners underneath the hills and mountains of southeastern Kentucky. But the landscape that was built to serve this work was fragile, leaving the people here extraordinarily vulnerable, especially after the coal industry shuttered so many of the mines and moved on. What remained were modest, unprotected homes and decaying infrastructure, and a land that itself, in many places, had been shorn of its natural defenses.

Last week, when a deluge of rain poured into the hollows, turning creeks into roaring rivers, overwhelming old flood records, killing at least 37 people and destroying countless homes, that vulnerability was made brutally manifest.

“When you have a century of billions of dollars and resources leaving, very little of it staying to create the infrastructure necessary for people to live lives, and it’s neglected as long as it has been,” said Wes Addington, a lawyer with the Appalachian Citizens Law Center in nearby Whitesburg, whose law office is now a flooded wreck, “when that’s combined with a really insane flood, it’s a catastrophe.”