Connecticut, abandoned mine maps
Neither federal file records a mine site or a mapped mine feature inside Connecticut. This page says so plainly, and names the office to ask and the federal archive that would hold a map if one exists.
Information only, no guarantee: read the limits at the foot of this page before you act on anything here.
This page
Every office on this page was opened and checked on Oct. 22, 2026.
Everything here can be wrong. This is information, not a guarantee: the two federal files can be wrong, incomplete or out of date, the boundaries and the geocoder can be wrong, a point is a location and not a property line, and nothing on this page says that a mine is or is not under any particular property. Do not buy, sell, move, or make any decision about a home or about your safety on this alone. Ask the state mine map office named here for the maps, and have a qualified engineer look at the ground.
Start here
Every card goes to the office that holds the record. Use the category buttons to narrow the list.
State records
An inventory of active and historic bedrock mines and quarries with a continuously updated web map.
Open official site Connecticut Geological Survey (DEEP), Connecticut Bedrock Mining Sites DatabaseFederal
The federal archive of maps of closed and abandoned mines, searchable by state, county, company and mine name; the images are sent on request through the map request form.
Open official site OSMRE National Mine Map RepositoryFederal
The federal inventory of abandoned mine land problems and the reclamation work funded against them, state by state and county by county.
Open official site OSMRE e-AMLISFederal
The national file of adits, shafts, pits and quarries digitised from the historical topographic sheets, each with the sheet name and the survey year.
Open official site USGS USMIN topographic mine featuresFederal
The USGS record of mines, prospects and occurrences with the commodity, the development status and the position of each site.
Open official site USGS Mineral Resources Data SystemThe map
To look at one address, one ZIP code or one town instead of the whole state, open the mine map hub search and enter it there: it takes a street address, a ZIP code or your browser location and lists what sits within the radius you choose.
Who keeps what
| What you need | Office or archive | What it can tell you |
|---|---|---|
| The geology, the seams and the published mapping | Connecticut Geological Survey (DEEP), Connecticut Bedrock Mining Sites Database | Which seams were worked in your county and what the state has digitised |
| A map of a closed mine the state does not hold | OSMRE National Mine Map Repository | The federal archive of more than 275,000 mine maps, searched by state, county, company and mine name |
| Whether a reclamation project is on record near you | OSMRE e-AMLIS | The federal inventory of abandoned mine land problems and the work funded on them |
County by county
Neither federal file holds a record inside any county of Connecticut. The county pages carry the state offices instead.
Town by town
30 towns with the most records inside its own boundary, of 61 towns that hold one.
| Town | Underground openings | Mapped features | Old mine sites |
|---|---|---|---|
| Bristol | 0 | 27 | 17 |
| Middletown | 0 | 15 | 26 |
| Shelton | 0 | 19 | 7 |
| Torrington | 0 | 6 | 18 |
| Danbury | 0 | 11 | 10 |
| North Haven | 0 | 16 | 5 |
| Willimantic | 0 | 4 | 16 |
| Bethel | 0 | 14 | 4 |
| Norwich | 0 | 12 | 6 |
| Derby | 0 | 6 | 7 |
| Meriden | 0 | 5 | 8 |
| Newington | 0 | 9 | 4 |
| Sandy Hook | 0 | 9 | 3 |
| Naugatuck | 0 | 11 | 0 |
| East Haven | 0 | 3 | 7 |
| New Britain | 0 | 2 | 8 |
| Ansonia | 0 | 0 | 9 |
| Waterbury | 0 | 7 | 2 |
| West Hartford | 0 | 2 | 7 |
| Bridgeport | 0 | 0 | 8 |
| Orange | 0 | 5 | 3 |
| Broad Brook | 0 | 6 | 1 |
| Portland | 0 | 5 | 2 |
| Greenwich | 0 | 0 | 6 |
| Cheshire Village | 0 | 4 | 1 |
| Northford | 0 | 4 | 1 |
| Quinebaug | 0 | 1 | 4 |
| Stamford | 0 | 4 | 1 |
| Groton | 0 | 0 | 4 |
| Lakeville | 0 | 0 | 4 |
The real document
Connecticut publishes no mine map viewer of its own, so the federal archive is the route.
OSMRE National Mine Map Repository is the federal archive. It holds maps of more than 275,000 closed and abandoned mines, the images are not downloadable, and they are sent on request: search the repository by state, county, company or mine name, then ask for the sheet by its number through the map request form or at nmmr@osmre.gov.
A mine map is the only document that shows the rooms, the pillars and the depth of cover under a given piece of ground. A point in either federal file is a location, not a property line, and it says nothing about what lies under any particular house.
Emergency
If the ground has opened, if a hole is swallowing water or soil, if a wall or a floor has moved suddenly, or if anyone could fall in, call 911 first. A subsidence hole can keep opening, and the edge of it is not safe to stand on.
Connecticut runs no abandoned mine land programme of its own, so a hazard on state or private land goes to the county emergency management office, and a hazard on federal land to the Bureau of Land Management or the Forest Service office that manages it.
Then tell the people who need the record of it: your insurer, your county emergency management office, and, if the hole is in a road or a right of way, the authority that maintains it. Photograph it with something in the frame for scale, write down the date and the time, and keep measuring it, because how fast it grows is what an engineer will ask about first.
Signs worth reporting before anything opens: doors and windows that stop closing, new cracks that run at an angle across a wall, a floor or a drive that dips, a sudden wet patch or a dry well, and a smell of sulphur or a warm patch of ground where snow melts first.
Cover
Connecticut runs no state mine subsidence insurance programme. Cover, where an insurer offers it at all, is an endorsement on a homeowner policy, and a standard policy excludes earth movement, which is what mine subsidence is.
Ask your own insurer in writing whether the policy covers subsidence from mining, and keep the answer. Seven states run a programme of their own: Pennsylvania, Ohio, West Virginia, Kentucky, Indiana, Illinois and Wyoming, with a protection programme in Colorado.
The data
Neither file holds a record inside Connecticut. That is the honest answer, and it is not the same as there having been no mining: a working that was never drawn on a topographic sheet and never entered in the mineral file is in neither count.
How the counting was done: every point in both files was placed inside the Census TIGER 2024 county and place boundaries by its own coordinates, not by the county name written in the file, because that name is blank or wrong often enough to matter. A point that falls outside every boundary is counted in no county and no town.
What the counts are not: a count of mines under houses. A single opening can lead to workings that run for miles, and a working with no opening on a sheet is in no count at all. Only a mine map shows the rooms, and only the offices named above hold the maps.
Everything here can be wrong. This is information, not a guarantee: the two federal files can be wrong, incomplete or out of date, the boundaries and the geocoder can be wrong, a point is a location and not a property line, and nothing on this page says that a mine is or is not under any particular property. Do not buy, sell, move, or make any decision about a home or about your safety on this alone. Ask the state mine map office named here for the maps, and have a qualified engineer look at the ground.
Straight answers
Open only the answer you need.
Not from this page and not from either federal file. A point is a location, not a property line. The only document that shows the workings under a given piece of ground is the mine map, and in Connecticut you ask the OSMRE National Mine Map Repository for it.
Call 911 first if anyone could be hurt. After that the report goes to your county emergency management office, because the state runs no abandoned mine land programme of its own.
Two federal files: the USGS Mineral Resources Data System and the USGS USMIN file of mine features digitised from the historical topographic sheets. Every point was placed inside the Census 2024 county and place boundaries by its own coordinates. For Connecticut that is 0 mapped mine features and 0 old mine sites.
A standard policy excludes earth movement, and mine subsidence is earth movement. Connecticut runs no state subsidence programme, so ask your own insurer in writing whether any endorsement is available and keep the answer.
It means a surveyor drew a shaft, an adit or a tunnel mouth at that spot when the sheet was made. It is a way in. The workings it leads to can run a long way from it, and the map of those workings is a separate document held by the offices named on this page.
No. This is a public records guide. The offices it names and links are the official sources, and everything on this page can be wrong: check it with them before you act on it.
All states
Every state page carries that state's own offices, its own counties and its own numbers.