OpenHistoricalMap/License
OpenHistoricalMap data is in the public domain under a Creative Commons CC0 dedication, unless noted otherwise. This means you can generally reuse the data however you want, for any purpose, without any restrictions. This public domain status extends to facts that we have individually sourced from works that are themselves copyrighted, for example, a start_date=* tag gleaned from a passing mention in a still-copyrighted newspaper article.
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Acknowledging OpenHistoricalMap
Although copyright law does not restrict or place any conditions on your use of public domain content, we greatly appreciate any credit you provide to OHM in your project. Acknowledging OHM – and, ideally, any relevant sources within the subset of OHM data that you reuse – will protect you and the OHM project from suspicions of plagiarism and help your audience discover the original sources in their own research.
You may present this acknowledgment in any reasonable manner. For example, on a digital map, you can mention OHM in fine print in the corner, linking to our homepage:
Or you can include a clearer acknowledgment on a separate credits page where you credit other sources:
- Map data courtesy of the OpenHistoricalMap project, in the public domain unless otherwise noted.
On a print map, you can place the acknowledgement in the legend. In a book, you can describe your use of OHM in a footnote, bibliography, or colophon. In an academic paper, you can cite us in various manners depending on what you used. Here are some examples to illustrate the kinds of details you might include; note that the exact formatting may depend on the style guide your paper conforms to:
- The project as a whole:
- “OpenHistoricalMap”. Washington, D.C.: OpenStreetMap U.S. Retrieved 22 January 2025.
- A specific date and place (see Zoom levels to determine the scale):
- OpenHistoricalMap (Map). 1:15,000. Black Rock City as of 1 September 2009. Retrieved 22 January 2025.
- A specific element:
- “Eiffel Tower”. OpenHistoricalMap. 21 January 2024. Retrieved 22 January 2025.
- An Overpass API query:
- Overpass API (22 January 2025). Regions of Spain under the Burgos plan (Report). OpenHistoricalMap. Retrieved 22 January 2025.
Copyrighted material
A small fraction of our data comes from copyrighted sources. We only accept copyrighted material that comes with an open license, such as Creative Commons Attribution 4.0. Each affected element has a license=* tag indicating the relevant license. Major sources are credited on our sources page.
As of January 2025, elements explicitly tagged with licenses amount to less than 0.01% of the database contents. Besides this content, most coastlines, bodies of waters, and streams were imported from OpenStreetMap under the Creative Commons Attribution-ShareAlike 2.0.