Abandoned Mines Are Still Collapsing Across The U.S.

Abandoned mines hidden beneath homes, roads and neighborhoods across the country can collapse with little warning, opening sinkholes, damaging property and, in rare cases, killing people.

An ABC News investigation published Tuesday found abandoned underground mines have caused dangerous collapses from California to Pennsylvania and New Jersey. Some mines date back more than a century, and government agencies don't know where all of them are.

Here’s what to know about the risk from abandoned mines and how to find out whether they may be near your home.

How Big Is The Problem?

There is no single comprehensive federal database showing every abandoned mine in the United States.

ABC News analyzed records from two federal agencies and found hundreds of thousands of documented mine locations. But many mines operated in the 1800s and early 1900s, when records were incomplete or nonexistent. Some underground workings are not discovered until the ground above them begins to sink or collapse.

The federal Office of Surface Mining Reclamation and Enforcement maintains an inventory of abandoned coal mine problems but says that inventory does not include all land and water damaged by past mining. States and tribes continue to add previously unknown problems as they are discovered.

Where Is The Risk Greatest?

The problem stretches across former coal- and hard-rock-mining regions of the country.

Pennsylvania coal country is particularly affected. ABC's analysis found communities there built directly over century-old underground mines. Colorado officials estimate that the state alone has more than 23,000 abandoned mines. Western states also have thousands of abandoned gold, silver and other hard-rock mines.

What Causes Collapses?

The ground above an underground mine can gradually settle, or it can fail suddenly.

Mine subsidence can damage foundations, streets, sewer and water lines, and other infrastructure. More dramatic collapses can create large sinkholes.

Federal officials list subsidence, open mine shafts, unstable highwalls and polluted water among the hazards associated with abandoned mine lands.

Recent incidents cited by ABC include a 35-foot sinkhole that swallowed a vehicle in a Pennsylvania driveway and a mine-related collapse that opened a hole more than 40 feet wide beneath a New Jersey highway. Fatal incidents have occurred in California, Pennsylvania and Colorado.

What’s Under Your House?

Homeowners can sometimes answer this question with a records search, but not always.

Historic mine maps, state geological surveys and abandoned-mine databases can help determine whether known mining occurred beneath or near a property. In some places, old paper maps are still being digitized.

But a property that doesn't appear on a mine map isn't necessarily in the clear. Federal officials say some old mines were poorly mapped or never recorded at all.

Who Is Responsible?

For coal mines abandoned before federal reclamation requirements took effect in 1977, states and tribes can use money from the federal Abandoned Mine Land Reclamation Program to address qualifying hazards.

The program prioritizes problems threatening public health and safety. Federal officials announced nearly $120 million in traditional abandoned-mine grants in February 2026 and hundreds of millions more in other federal abandoned-mine funding.

But the backlog is substantial. Federal officials told ABC that reclamation efforts often remain reactive, with some dangerous sites receiving attention only after a collapse or other incident exposes them.

The problem extends beyond coal. Federal officials have a longstanding reclamation program for qualifying abandoned coal mines, but ABC reported there is no comparable consistently funded federal cleanup program covering all abandoned gold, silver, iron, uranium and other hard-rock mines.

If Ground Starts Sinking

A new depression, crack, hole or sudden change in the ground around a home in a historic mining area shouldn't be entered or investigated up close.

Keep people and pets away from the area, and contact local emergency officials or the state agency responsible for abandoned mines or geological hazards. Old mine openings and sinkholes can be unstable and may continue to collapse.

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