us-places-mcp

us-places-mcp

An MCP server for where things were, then. Records follow the jurisdiction that held a place on the date of the event, not today's: a 1795 deed for a farm now in Greene County, Pennsylvania, is in Washington County's books, because Greene was carved out the next year. This server answers the questions that decide which office to write to:

• Which county held this spot on that date? From the Newberry Library's Atlas of Historical County Boundaries, which records every creation and boundary change of every US county from 1629 to 2000, dated to the day, with the act behind it. OpenHistoricalMap imported the atlas and serves it free (CC0); this server asks it.
• Where is this land description on the ground? "E½NE Sec. 18, T84N R39W, 5th P.M." becomes a centroid, a bounding box and BLM's ids, from the Bureau of Land Management's national Public Land Survey data. A map pin becomes a land description the other way.
• Where is the case file behind this land patent? The patent is the end of a process. The file at the National Archives holds the application and, for a homestead, years of residence, witnesses and citizenship papers. The server says which file and which series, and builds the search.
• Where was Mount Hope Cemetery, or Hines Corners? USGS's Geographic Names Information System (GNIS) names and places every feature it knows, including vanished towns marked "(historical)". In 2021 it dropped cemeteries, churches, schools, post offices and other built features; the server also searches the archive USGS kept from August 2021, and says which answered.
• Which post offices were there, and when? Richard Helbock's list of every US post office from 1639 to 2000, geocoded by Cameron Blevins: 166,140 offices with the years they opened and closed. A post office is often the only trace of a hamlet.
• Which old maps show the spot? Every USGS topographic map since 1884 that covers a point, oldest first, with links to the scans.

Nothing here writes anywhere, and nothing here keeps a family tree. It sits well beside nara-catalog-mcp, which can run the archive searches this server builds, familysearch-mcp and snac-archives-mcp.

This is an independent project. It is not affiliated with, endorsed by, or supported by the Newberry Library, OpenHistoricalMap, the Bureau of Land Management, the US Geological Survey, Harvard Dataverse, the dataset's authors or the National Archives.

Tools

The server publishes twelve tools, all read-only and annotated so for the client. Five make no network call at all.

Jurisdiction at a date

Tool	Purpose
county_at	The county (or counties) that held a point on a date: a day, a month or a year. Returns the holder, its dates, the event and statute that made it, the whole chain of counties for that spot, changes within a year (check those by hand), and whether two governments contested it.
county_history	Every version of one county: created when, from what, and each later change, with statutes.

Federal land

Tool	Purpose
parse_legal_description	Read a land description, however it is written (E½NE, E2NE, E 1/2 NE 1/4, "the east half of the northeast quarter", GLO's padded 0840N, lots, several tracts), into its parts, with quarter-quarters and warnings for anything guessed. Offline.
plss_locate	Place a description on the map: centroid, bounding box, acreage and BLM's ids, to the township, section, quarter-quarter or lot.
plss_from_point	Name the survey tract at a point: township, range, section and quarter-quarter.
public_land_state	Was this state federal land? If not, who granted first title and where those records are; if so, its meridians and special cases. Offline.

Vanished places and old maps

Tool	Purpose
find_place_name	A named place in GNIS: its point, class, state and county. Searches the live GNIS and, given a state, the archive of August 2021 that keeps the cemeteries, churches, schools, post offices and buildings GNIS dropped that year; says which answered.
post_offices	Which US post offices existed, 1639-2000: by name, by state and today's county, or around a point, and in a given year. Each with its years, whether it ran continuously, and its point if it was geocoded.
historical_topo_maps	Every USGS topographic map covering a point, oldest first: date, scale and quadrangle, with GeoPDF, GeoTIFF and JPEG preview links, and a TopoView link for JPEG and KMZ.

From patent to case file

Tool	Purpose
find_land_entry_file	From a patent's Authority: the kind of entry, what its file holds, which National Archives series has it, ready-made arguments for nara-catalog-mcp's search_records_advanced, and how to order the file if it is not online. Offline.
glo_links	A link to a search, or to one record, on BLM's General Land Office Records site, for you to open. Offline.
cache_status	This session's live calls and cache hits, and the datasets downloaded so far. Offline.

Setup

You need Python 3.11 or later and uv. There is no key to request.

uvx us-places-mcp

or from a clone:

git clone https://github.com/ianderso/us-places-mcp
cd us-places-mcp
uv sync
uv run us-places-mcp   # stdio server, usually launched by the client

Claude Desktop

{
  "mcpServers": {
    "places": {
      "command": "uvx",
      "args": ["us-places-mcp"]
    }
  }
}

If the server fails to start because uvx cannot be found, give the full path that which uvx prints as the command.

Claude Code

claude mcp add places -- uvx us-places-mcp

Configuration

Nothing is required. A .env file in the directory the server starts in supplies anything the environment does not; only that directory is read.

Variable	Meaning
US_PLACES_OVERPASS_URL	OpenHistoricalMap's Overpass endpoint. Default https://overpass-api.openhistoricalmap.org/api/interpreter.
US_PLACES_PLSS_URL	BLM's national PLSS map service. Default https://gis.blm.gov/arcgis/rest/services/Cadastral/BLM_Natl_PLSS_CadNSDI/MapServer.
US_PLACES_GNIS_URL	USGS's GNIS map service. Default https://carto.nationalmap.gov/arcgis/rest/services/geonames/MapServer.
US_PLACES_GNIS_ARCHIVE_URL	The folder of GNIS state files from August 2021. Default https://prd-tnm.s3.amazonaws.com/StagedProducts/GeographicNames/Archive/MainDomestic.
US_PLACES_TNM_URL	The National Map's TNM Access products API. Default https://tnmaccess.nationalmap.gov/api/v1/products.
US_PLACES_DATAVERSE_URL	Harvard Dataverse, which holds the post-office dataset. Default https://dataverse.harvard.edu.
US_PLACES_CACHE_DIR	Response cache directory; downloaded datasets go in its data folder. Default ~/.cache/us-places-mcp.
US_PLACES_TIMEOUT	HTTP timeout in seconds. Default 60.
US_PLACES_CONTACT	An email address or URL added to the User-Agent, so the services can reach you. Optional, and courteous.

Every URL must be https. Their hosts, and Dataverse's file store (dvn-cloud-iqss.s3.amazonaws.com, where it redirects downloads), are the only ones the server will contact.

Being a good guest

OpenHistoricalMap's Overpass server runs on donated capacity and publishes no rate limit. The server sends one request at a time to each service, two seconds apart for OpenHistoricalMap, half a second for BLM and a second for USGS and Dataverse, joins identical calls in flight, and caches answers on disk: county answers for 90 days, GNIS and map answers for 30, survey answers until you pass refresh=true. A 429 or a 5xx is retried three times with back-off, then reported as rate_limited or upstream_error, which is never the same as "nothing here".

Downloaded data

Two sources are files rather than services, so the server downloads them once and reads them locally. Nothing is downloaded until a tool needs it, and the result that triggered a download says so: what, how big, how it was checked and where it was saved.

Data	When	Size	Checked against
US Post Offices (Blevins and Helbock, doi:10.7910/DVN/NUKCNA, CC0)	The first post_offices call	31 MB download, 21 MB on disk	The MD5 Dataverse publishes for the file
GNIS state file of 25 August 2021 (USGS, public domain)	The first find_place_name search in that state	Up to 17 MB per state (Pennsylvania 9.8 MB); only the dropped classes are kept, about 6 MB for Pennsylvania	The ETag USGS's bucket reports (an MD5, or the MD5 of the upload's parts)

Both are stored as SQLite files in data under the cache directory (~/.cache/us-places-mcp/data by default), never in the repository. A file that fails its check is deleted and the tool reports download_failed. cache_status lists what is there; delete the folder to start again.

How to read what comes back

• The county then, not now. A record was made by the county that held the place on the day. A new county does not take its parent's earlier records, so a deed from before Greene County existed is in Washington County's books still.
• Check dates near a change. boundary_change_within_a_year lists changes close to your date. Laws took effect on stated days, but offices took time to organise; records from those months can be in either county.
• "Attached to". Before an area was organised as a county it was often attached to a neighbour for administration, and that neighbour kept its records. county_at reads this from the atlas's event text.
• Contested ground. Pennsylvania and Virginia both governed the Waynesburg area in the 1770s, and similar disputes ran elsewhere. "status": "contested" means look in both governments' records.
• The atlas files counties under today's state. Monongalia County was created by Virginia but is filed under West Virginia; the event text says which government acted.
• The atlas ends in 2000 and holds counties only: not towns, townships or parishes as church units.
• A located tract is not a house. A section's centre is up to half a mile from any point in it, and BLM's data is a modern compilation that can differ from the original plat near correction lines and water. Lotted sections (along a township's north and west edges, or by water) have lots where a regular section has quarter-quarters.
• A parse is a reading of a reading. parse_legal_description keeps the original text and says what it guessed: a section number with no "Sec.", a meridian taken from the state.
• A patent proves a conveyance, on its signature date. The entry was years earlier: homesteaders lived on the land five years before final proof, and mid-century backlogs put years between purchase and signature. The Homestead Act took effect in 1863, so an "1856 homestead" in a family story is a cash, credit, preemption or warrant entry.
• The patentee may never have seen the land. Military bounty-land warrants were bought and sold; the veteran is in the warrant file, the patentee may be a speculator.
• No federal patents in state-land states. The thirteen colonies, Maine, Vermont, Kentucky, Tennessee, West Virginia, Texas and Hawaii granted their own land. A nil search there means nothing; public_land_state says where first title was recorded.
• Old GLO links are dead. BLM rebuilt glorecords.blm.gov in July 2026, and older record links now land on the home page. Cite a patent by its accession number, document number, state and signature date.
• GNIS names are today's official names, not the spellings in old records. GNIS writes out Mount, Fort and Saint and drops possessive apostrophes (Pikes Peak); the server does the same to what you type. A place that is gone is often listed as "Name (historical)". A GNIS county is today's county: pass the point to county_at.
• The 2021 archive is frozen. Cemeteries, churches, schools, post offices and buildings are as GNIS held them on 25 August 2021, and USGS no longer maintains them. topo_quad names the 1:24,000 map each was read from.
• A map's date is the date of its survey or edit, not of the ground on the day you care about, and a reprint keeps the old date. Several scans often share a quadrangle and a date: later printings or other copies of one edition. Compare them. At 1:62,500 and larger, maps show roads, churches, schools and cemeteries, and often houses; a house symbol names no one.
• A post office's years are Helbock's. A renaming, or a change to a branch, ends one record and may start another, so "discontinued" can mean renamed. An office closed for under ten years stays one record, marked continuous: false. Moves within a town are not recorded.
• A post office's county is today's. Helbock listed the county in which the site lies now. For the county that kept the records then, pass the office's point and year to county_at.
• A third of the post offices have no point. Blevins placed an office by matching its name to a GNIS feature; offices that matched nothing have no coordinates, so a search around a point misses them. Search the county too. gnis_match shows what each was matched to and how closely.
• Postmasters' names are in the Records of Appointment of Postmasters at the National Archives (microfilm M1131 for 1789-1832, M841 for 1832-1971).

Deliberately not here

• Searching GLO itself. The rebuilt site has no public API. The server builds links for you to open; it does not fetch the site.
• Townships and church parishes as jurisdictions. The atlas is counties only; GNIS names places but says nothing of who governed them.
• Writing anywhere.

Security

• A fixed set of hosts. A request hook refuses any request not for a configured service or Dataverse's file store, so a value a model passes in cannot make the server fetch another site. A download follows a redirect only to one of those hosts.
• Downloads are checked before they are kept, against the checksum the publisher states, and are capped in size.
• Inputs are validated before they reach a query: coordinates as finite numbers in range, states and GNIS classes against tables, survey numbers as digits, and a county name escaped character by character into the Overpass query. A place name reaches GNIS only as find's search text, never inside a where clause, and local searches use bound parameters.
• Event, statute and place-name text is data. It comes from the sources and reaches the model verbatim; the server's instructions tell the model to treat it as data, never as instructions.

To report a vulnerability, see SECURITY.md.

Development

uv sync --extra dev
uv run pytest                      # mocked with respx; never touches a service
uv run ruff check .
uv run ruff format --check .
uv run python -m tests.live_check  # a few paced calls to every live service

See CONTRIBUTING.md, docs/API-NOTES.md for what was observed of each service and when, and docs/DESIGN.md for why the server is shaped this way.

Credits

County boundaries: the Newberry Library's Atlas of Historical County Boundaries (John H. Long, editor), as imported into OpenHistoricalMap and released under CC0. Survey data: the Bureau of Land Management's National PLSS (CadNSDI), a US government work. Place names: the US Geological Survey's Geographic Names Information System, a US government work. Maps: USGS's Historical Topographic Map Collection, through The National Map. Post offices: Cameron Blevins and Richard W. Helbock, US Post Offices, Harvard Dataverse, doi:10.7910/DVN/NUKCNA, released under CC0.

License

MIT.