Before there was oil and gas, coal mining swept through Oklahoma.
"The coal mining industry is what drove the economy of the United States for a great deal of time," said Mike Sharp, assistant director of the Abandoned Mine Land program.
"It was very dangerous work."
Coal miners worked long hours in poorly lit conditions. Stale air filled the lungs of those brave enough to venture into the deepest mines.
But what was considered hard work, benefited all Oklahomans as trains transporting goods were fueled by coal.
It was a thriving business across the Sooner State until the discovery of diesel fuel.
"The mines started drying up back then," Sharp said.
The remnants of a livelihood sit abandoned. The soil, although rich in history, poses a danger to society.
"Here in Oklahoma, we've had 25 deaths as a result of abandoned mine land hazards," Sharp said.
Rugged land and washed out roadways have caused issues.
"Ranging from drownings all the way to folks venturing into underground shafts, and hitting a point where there was no air," Sharp said.
But now, one Oklahoma program is picking up the slack, and reclaiming old mines, above and underground.
"We're eliminating dangerous high walls, eliminating the hazardous water bodies, we're eliminating other dangerous hazards as a result of that," said Robert Toole, director of the Abandoned Mine Land program.
The Oklahoma Conservation Commission is traveling Oklahoma, filling in old mines and repacking the land with soil. With more than 72,000 acres of abandoned mines, the Abandoned Mine Land reclamation program covers 16 counties across Oklahoma.
"It's important for us to find the oldest map we can find, because that's going to show us the earliest mined out areas of these map," Toole said.
Dating back to the 1920s, AML is reconfiguring original maps into layouts of today's land. With nearly $122 million worth of high priority coal mines to fill, the road ahead is a long one.
"We have to establish priorities each and every year to determine which sites we reclaim and which sites we defer, just really based on the hazard itself," Toole said.