Abandoned mines in the United States

No federal count exists. USGS's 2025 fact sheet says that as of 2025 there is no comprehensive national inventory of abandoned mine features, and that the detailed database USMIN is building for the Interior Department will not be published, because agencies do not want individual workings locatable. GAO reported in 2020 that federal agencies had identified at least 140,000 abandoned hardrock mine features on federal land and estimated more than 390,000 more not yet in any database.

Each figure here is a count of records in a named public inventory. A USGS feature is a symbol on a historical topographic map: an adit, a shaft, a prospect pit, a quarry. It was there when the map was surveyed; it may since have been sealed, reclaimed, built over, or reopened as a working mine, and the map does not say which. An OSMRE row is a problem the abandoned mine land program tracks, not a mine, and one mine can produce several. An MSHA mine is a registered operation whose operator reported abandonment, which is why that record starts in the 1970s and misses everything earlier.

Counties are assigned from coordinates. Every feature is placed in a county by its location against the Census 2023 county boundaries rather than by the county name in the source file, which is missing, truncated or wrong on a few thousand rows. Mapped areas are located by their centroid.

The three records overlap and do not reconcile. A sealed shaft can appear as a USGS symbol, an OSMRE vertical-opening problem and an MSHA abandoned mine at once. The pages never add them into one number.

They are also not the same universe. USGS puts 87 percent of its map symbols, 633,181 features, in the hardrock category (IMCC-NAAMLP Hardrock AML Report, page 48; the denominator there is the 725,690 symbols recorded from the maps, rather than the 597,612 in the consolidated release counted on this page). OSMRE's inventory is the opposite: it is the coal abandoned mine land program, funded by a per-ton tax on active coal mining since 1977, and of the problems whose program name says which, 36,739 are coal against 4,074 non-coal. MSHA's register sits between them at 43,897 metal and nonmetal mines against 34,407 coal. So the USGS column and the OSMRE column are not two counts of one thing, and the difference between them is not a backlog: hardrock reclamation is a separate and far smaller federal program. West Virginia is the clearest case: the state supplied its coal AML geodatabase to the USGS effort and no hardrock features at all, which its Office of Abandoned Mine Lands confirmed to us on 8 September 2026.

The map undercounts the ground. Measured against state inventories in California, Colorado, Nevada, Utah, Virginia and Wyoming, the IMCC-NAAMLP report found 3 to 10 actual features on the ground for every USMIN map point, depending on the state. At a conservative 3 to 1 it estimates 1.8 million hardrock abandoned-mine features nationally, about 750,000 of them imminent physical safety hazards, and puts the cost of addressing the physical hazards at $11 billion at least (IMCC-NAAMLP Hardrock AML Report, pages 52-53). That is the report's estimate, not a count of any record on this site.

MSHA's "Abandoned" is a regulatory status, not a description of the ground. An operator reports the status, and reporting it ends the inspection obligation, so the bucket also holds operations that are merely between jobs. Portable crushers are the clear case: they crush for a month, shut down, move, and start again, and MSHA carries them as Abandoned in the gap with the equipment still on site. The data agrees. Of the 78,304 mines carrying Abandoned or Abandoned and Sealed with a status date, 983 were inspected by MSHA more than 90 days after that date and 1,258 have been inspected in the last two years, which is not something that happens at a genuinely abandoned mine. 9,828 of them are registered portable operations. MSHA does keep separate Intermittent and Temporarily Idled codes, which is exactly why the Abandoned bucket's contents are a judgement rather than a fact. Read this column as "MSHA is not inspecting it", not as "nobody has worked here in decades".

Neither OSMRE figure is a state program's own live inventory. West Virginia's AML office ran its own AMLIS report for us on 8 September 2026: 5,227 problem areas, 2,480 of them completed and 3,092 with work outstanding. The public extract gives 5,477 for the state, slightly more rather than fewer. We cannot say from the published file which 250 areas account for the difference, and do not guess: the state's is the live figure and the extract is a periodic snapshot of it. Their two categories also overlap, since a reclaimed area can need work again when a new feature turns up beside it or an old project fails with age, so a state's completed and outstanding counts sum to more than its total. Where the two disagree, the program's number is the one to use.