State of
OpenHistoricalMap
Mapping the world's history, openly.
Speakers Minh Nguyễn · 1ec5 · Ruben Lopez Mendoza · Rub21
State of the Map 2026 · Friday, August 28 · La Réunion
Minh · 1ec5
OpenHistoricalMap
Ruben · Rub21
OpenHistoricalMap
Almost every map shows only the world of today. But every street, border, and building is the result of centuries of change — and maps forget.
What if the map
could remember?
OpenHistoricalMap = OpenStreetMap
Every street, building, or border carries when it existed. The map gains a fourth dimension: time.
What's in the map
From empires to small districts. The Spanish Empire alone: 162 time slices, 1492 → 1899. Napoleon's France, 1808 → 1814.
From Roman roads to modern avenues.
Churches, factories, homes — built and demolished.
Rail networks that grew and later disappeared.
Rivers, coastlines, forests — as they were in the past.
Cities, towns, villages — renamed, moved, or gone.
3.6M dated features in total · average mapped year: 1960 · counts from OHM taginfo & Overpass, August 2026.
See a city change, century by century
How people map
One open dataset, three editors — log in with your OHM account.
Much more than a map
overpass-turbo · osmcha · planet · taginfo — the same OSM tools, running on historical data.
How the OHM ecosystem is built
A fork of the OSM website, adapted to work with dates — plus a time slider on the map.
A fork of iD with start_date and end_date fields in every edit.
The same OSM tools, adapted to answer when — not just where.
Our own vector tiles, filtered by date — served with Martin.
taginfo, OSMCha, tasking manager, planet dumps — all running on OHM data.
Take an OSM tool, fork it, add dates. JOSM and Vespucci work without changes — just point them to OHM.
Take the data with you
Time-aware queries: ask for any place at any date, get GeoJSON back.
The whole database, downloadable — same formats as OSM.
Style your own historical map — tiles served as TileJSON, filtered by date.
embed.openhistoricalmap.org — put a live historical map in any website.
All of it CC0 — no permission needed, ever. Your archive, your research, your product.
“A time machine, brought to you by the community.” OpenHistoricalMap at the North American Cartographic Information Society (NACIS) · 2024
How the project runs today
2,177 active mappers — zero paid staff. Mapping, code, and operations all run on donated time.
No dedicated funding. OSM US charter-project development funding ended in 2025. Individual donations help pay the costs.
Small and low-cost. The full OSM stack — website, API, tiles, tools — maintained by a few volunteers.
Fragile but alive. Growth needs more people — and real funding.
TODO Minh
A growing ecosystem of partners
Sanborn fire-insurance maps georeferenced and traced into OHM — recurring joint workshops since 2023.
Atlas of Historical County Boundaries imported — two centuries of US boundary changes.
Linked with Wikidata and Wikipedia — map features connected to the world's encyclopedia.
Local historical societies, universities, hack-a-thons — from Erie Canal to Richmond to Vanderbilt.
Source: openstreetmap.us OHM archive — confirm the final picks with Minh.
What's next — and what we need
Where we want to go
- →TODO · upcoming development #1
- →TODO · upcoming development #2
- →TODO · upcoming development #3
What we need to get there
- 💸Funding · ~$TODO/year runs the whole platform — grants, sponsors, or donations via OSM US
- 🛠️Maintainers · more people taking care of the tools, not only the map
- 🤝Partners · universities, archives, museums, libraries
openstreetmap.app.neoncrm.com/forms/ohm · TODO: roadmap items with Minh + real annual infra cost.
History needs mappers — and supporters
Mappers: map things that already happened — a battle, an old railway, a building that is gone, your city’s past. Everything you map stays public and alive.
Organizations: if your archive, research, or product works with history — partner with us, fund us.
Let's keep history alive
openhistoricalmap.org
keep history alive
TODO: deck URL
Minh Nguyễn · 1ec5 · Ruben Lopez Mendoza · Rub21